Thankfully, Captain Marvel's suit in the upcoming film appears to be completely real, for the most part. The film itself evidently has quite a serious tone, and everything shown in the trailer seems to have been rendered to fit that tone. You won't find any goofy looking aliens or poorly rendered light constructs in this film. Speaking of which, we haven't yet received a good, solid look at Captain Marvel's powers, which might be a good thing, indicating that Marvel is taking Danvers' character seriously and not trying to entice audiences with cheap, flashy effects.
Even if you compare the film's depiction of aliens to the world presented in Guardians of the Galaxy, you'll see that there are a lot of differences. Guardians was fast-paced and full of color, while Captain Marvel seems to be much more grounded and, visually, a little more focused.
But why all the effort? To answer that, we have to look at the history of Carol Danvers as a character and her significance in the comics.
When Carol Danvers was introduced back in the 1960s, she was written as a strong female character, which was appallingly rare at the time. Throughout her earlier stories as Ms. Marvel, she stood up against sexism and became a feminist icon. Her character was tragically misused in the 1980s in such comics as the infamous Avengers #200, and it wasn't until the 2000s that Marvel began to rectify that problem by turning her into a more prominent superhero and writing worthy stories for her.
She's more than just another superhero. If people are busy comparing the film to Green Lantern, they'll miss everything that makes Carol Danvers a great character. Making changes to her story for the adaptation ensures that people get to appreciate Captain Marvel as a singular hero with a unique story, a combination that might allow the film to ultimately have the same impact on the Marvel Cinematic Universe as Wonder Woman.
That film's critical acclaim and box office success got audiences discussing the depiction of powerful women in mainstream cinema. It also proved to studios that female superheroes can succeed if depicted properly, which was the kind of impact Marvel was going for in the '70s.
People are slowly starting to see that Captain Marvel as a character isn't just Marvel's answer to Green Lantern. The release of the trailer has proven that the MCU's depiction of the character is so different that it no longer makes sense to compare the two, if it ever did. It's safe to say that Marvel Studios has finally distanced Captain Marvel completely from Green Lantern.
Debuting in theaters on March 8, 2019, Captain Marvel is directed by Anna Boden and Ryan Fleck and stars Brie Larson, Samuel L. Jackson, Ben Mendelsohn, Djimon Hounsou, Lee Pace, Lashana Lynch, Gemma Chan, Algenis Perez Soto, Rune Temte, Mckenna Grace, Clark Gregg and Jude Law.