he's identical to Vegeta
my theory is that Toriyama secretly likes and felt bad about killing him so he reused his character design because he had a slight pang of regret for killing him off
that said at the time Toriyama claimed he hated Vegeta and resented the fact that fans liked him
he has recently said he's changed his mind and likes Vegeta now
he has a very funny way of showing it
you can assume that if you want but he's not, the literal actual explaination is that Toriyama forgot what color his hair was and Toei was too embarrassed to tell him his character design sheet was colored wrong
I'm told the Manga is worse
the person who told me the gist said they actually like the future Trunks arc
(most other people I've spoken to say the Manga is better though)