With Goku being the protagonist of the Dragon Ball franchise, he's been basically everywhere and has done seemingly anything that any human could dream of wanting to do. Despite this, there are a lot of characters in the story who have proven to be capable of doing things that Goku can't.
Trunks is one of these people. He was introduced in the Cell Arc of the original Dragon Ball manga as the son of Vegeta from the future, and has since been re-introduced as a child during the present. This list will be detailing things that both the Trunks from the future and from the present are capable of doing that Goku isn't.
Perhaps the most iconic thing about Trunks is that he's one of the few Dragon Ball characters that chooses to wield a weapon, and Trunks's weapon is a blade. It was shown that he started wielding a sword in the future under his training with Gohan, and his sword is implied to have been forged by him as well.
Trunks has wielded his sword during fights against very powerful foes. He used it to kill Frieza, and he used it against King Cold before killing him with just his Ki blasts. He later ended up wielding the Z-Sword against Dabura, and even when it was broken, he used it in the fight against Zamasu.
As mentioned earlier, Trunks was trained by Gohan in the future, and one of the things he learned from him was the ability to use the Masenko. This is a Ki blast technique that originally taught to Gohan by Piccolo, and a less-advanced version of the well-known Special Beam Cannon.
While most fans have probably forgotten the times he's used it, most of them were during the Zamasu Arc. Trunks had used the Masenko on Black to distract him during the first time he fought them alongside the other Z-Warriors, and he used it against him a second time afterwards when he fought him head-on with his sword.
This might be a given, seeing as Goku already isn't capable of using a sword, but there is more to the Burning Attack than just being able to wield a sword. It requires a lot of hand signals (at least, hopefully he has a reason for doing them), and he also finished the attack with a Ki blast.
This technique is very iconic in Trunks's arsenal, having used it in his first appearance against Frieza and King Cold. He's used similar sword and Ki combinations in his later fights, but none are quite like the Burning Attack.
Goku is capable of using the Metamoran Dance to fuse with another warrior, temporarily becoming one in the midst of battle. We saw him teach this ability to Trunks and Goten during the Buu arc. Goku also demonstrated this ability when fighting alongside Vegeta against Broly in Dragon Ball Super: Broly.
But, as we know, you need to be equal in power to fuse with someone, and even Goku would have a hard time lowering his Power Level to be equal to Goten's. The Metamoran Dance wouldn't work properly, either, because of the height difference. Even if both of those things were wrong, he still wouldn't become Gotenks in the end.
Trunks has traveled back in time repeatedly to ask the Z-Warriors for help in his quest to save the future. He did this both in the Cell Arc and the Zamasu Arc. The Time Machine was made by the Bulma in the future, and there's no known Time Machine from the present.
In Dragon Ball Z, it's shown that Goku actually has trouble driving, as shown when he and Piccolo were trying to get their driver's licenses after Chi-Chi's request. Considering he can barely drive, it's safe to assume he isn't capable of properly piloting the Time Machine.
Trunks is known to have an attack called Finish Buster, where he throws his hands into the air and then blasts a beam similar to the Masenko towards the opponent. The Heat Dome Attack is a developed version of this attack that fires in all directions.
The only known time that Trunks used the Heat Dome Attack was when he went back to his timeline and used the attack to finish off the First Form Cell that was still roaming the world, looking for the Androids that Trunks already destroyed. 'Finish off' might be an understatement; it was his first and last attack.
During the Zamasu Arc ending, Goku and Vegeta performed the Potara Fusion to fuse into Vegito for the first time since the Buu Arc. After failing to defeat Merged Zamasu, Trunks was the final warrior left standing before him, and he attained a new, enhanced variation of the Super Saiyan 2 form called Super Saiyan Rage.
The form emanates a blue aura around the normal golden aura of the Super Saiyan 2 form, and he is able to sense God Ki, which is an implication that he himself has God Ki. Promotional material suggests that this form was born from Trunks's rage pushing him beyond his limit, as a reaction to Zamasu's actions.
Unlike Goku, who has almost never gone all out from the beginning of fights no matter how high the stakes are, Trunks almost always tries his hardest right from the off.
Trunks is shown holding back far less than Goku does, even in his first battles against Frieza and King Cold. He wanted to immediately finish off Cell during the Cell Arc, and when he went back to his timeline, he had no mercy for the Androids. His fight against Dabura was also similarly intense, and he tried his hardest during all of his battles against Black and Zamasu.
Whenever Trunks went into his Super Saiyan Rage form, he gained the ability to channel Ki through his shattered Z-Sword for his fight against Merged Zamasu. Trunks wasn't capable of winning with his own power, however. He had to make a Spirit Bomb out of the spiritual energy left of the remaining survivors in his timeline and the warriors of the past.
Ignoring the fact that he was never even shown learning how to make a Spirit Bomb, he channelled it through the Z-Sword and used it to finish off the physical form of Merged Zamasu, which made his soul merge with the cosmos.
While Goku has worn different bizarre articles of clothing throughout the years (ranging from different Gi to the uniform he wore after coming back from Yardrat), and while fans will argue that he rocked everything he's ever worn, it would be hard to envision him actually pulling off Trunks's outfit like he does.
Trunks literally tucks in his tank top with a big belt that doesn't even match the colour of his outfit, he wears a jean jacket that is too small for him with the collar popped, and then he literally carries a sword with a buckle and all. Let's face it, Goku just can't handle this attire.