WARNING: The following article contains spoilers for the third season of Lucifer.
Most people know Tom Welling from his days playing Clark Kent on Smallville, the WB/CW series that gave us Superman before he became the superhero we all recognize from the comic books. That role defined Welling's career, which is why it's so refreshing to see him extend his repertoire with another show based on a DC Comics series: Lucifer.
When Welling takes a role, he is committed to it, as you can see when looking back at his career. He served as a director and executive producer for Smallville, fighting against changes he felt went against the character the series had developed over the course of a decade. When the show ended, we didn't see much of Welling, but after six years, he has returned to television, this time as the no-nonsense Lieutenant Marcus Pierce.
Smallville did a fantastic job at exploring Clark Kent's growth and struggle in accepting his role as something of an outsider in human society. Welling made the character his own, refraining from reading the comics or watching Christopher Reeves' portrayal in the Superman films, and yet there was something familiar and fitting in his portrayal. This is a near god-like character with very human struggles and small town values, and Welling played him almost perfectly.
Superman is a famously optimistic, good-hearted superhero, written to embody all the virtuous qualities one would expect from their heroes. He's a force for good and a role model -- but Welling didn't always play him that way. The compassion and small town values were all there, which allowed audiences to feel that sense of innocence emanating from the character, but for the most part, Clark Kent as depicted in Smallville was still finding his way. He was struggling to find his place between his sense of responsibility and the fact that even with all his power, he would never be able to save everyone.
Welling's Clark Kent was still sorting himself out and growing into the superpowered kryptonian guardian that would save the Earth from the likes of Lex Luthor, Brainiac and Doomsday. The bottom line is, Clark Kent is wildly different from the character Welling plays in Lucifer.