Yeah, this is probably going to turn into a stupid to ask question, But what the hell!
lets say we have a Wookiee Character with strength skill level 5 and a human character with strength skill level 5. In a roleplay the Wookiee character would still be stronger then the human dispite having the same skill levels, is that correct?
This would also apply to all other races in the combine. (example - Yam'rii/Trandoshan/Gamorrean stronger then Twi'lek/Cerean/Chadra-Fan.)
I'd say not really. The wookiees being stronger is given with their racial bonus to the Strength skill. If the Human spends time and energy (XP) to bulk up their muscles and get stronger, then yes they could be equivalent in strength.
It sorta breaks into two diffrent categories for the levels though. Degrees and 'levels of practice' work for learn't skills such as R&D, Med Treatment and Piloting, but it doesn't work for most general skills which are physical abilities and atrabutes. Not sure which category Stealth fits in though, for most races it would merely be your ability to sneak, but for Defel or Clawdite its more of a physical ability.
I think you think about it too much =P Its not always just about your skill points in RP, sure build your character around them but you don't have to tell people your skill levels in RPs, they might make difference when you want to do something crazy and tell them to your GM to give him reason to let you do that (like for example wanting to get out of hyper very near to a planet and justify it by having piloting skill 5 or something like that) but personally I never had to do that yet. If it makes sense for your character, like Defel not being able to be seen by others in shadows or something then I don't think it really matter what your Skill is.