Alright. It appears that I wasn't clear about something here. The reason that I left role playing out of my original comparison was because the question was about mechanics.
I think that was clear enough!
If skills are optional, and the GM decides not to use them, how is any one character special at doing something beyond their stat?
Ok, skills aren't of course the only possible way to make a character better at something... Currently in 5e we have classes features, subclasses features, background traits and lore, and feats (I left racial benefits out since they don't make you better than any member of your own race).
The mechanics are plenty, but the problem is that currently each mechanic has a very limited number of options. Among feats there is basically one of them for being a better <insert favourite weapon style> except archery which has a second but it's very specifically magic. The current list of feats is extremely short really...
That said, a rough comparison between 3e core and 5e playtest rules, tells me that indeed there is less room for customization.
However if you keep in mind that Advanced D&D 5e will have a rule for mixing and matching subclasses features (and why not even mixing subclasses of different classes, if the features still work for the other class), this will give a huge additional freedom, overall possibly even better than 3e despite the lack of skills in core (but of course you need to have a DM who allows this Advanced customization).
Beyond that, you're going to have to wait for splatbooks, but that was also true in previous editions. Honestly, when I started playing in 3e more than a decade ago, I noticed quite soon that the PHB feats were not enough IMHO, despite their apparent high number.
I really want to know how a person with a particular concept would build their character if the current means of doing so is denied them.
Honestly, I think first of all I would just downsize the concept's level of details. If the RPG I'm playing doesn't allow it, and I can't change the edition I'm playing, there is no use to fight it.
Second, I would play my PC in a way that focuses on doing more often what is supposed to be her signature. I wouldn't call this "roleplaying it" because it sounds snob. I just mean that if the concept is that of an expert climber, I'd make her take as many climbing opportunities as possible, even tho she's not better than the others at doing do. "Climber is who the climber does" so to speak
