So then if there really isn't a difference, since I really dig the look of the Telecaster guitar, I could take a telecaster body, change some crap around, and wind up with a bass?
Bassically, yes. But you may not like the results.
Much depends on your skill level at "moving things around" and specifically what you move and how you do it.
It's a really big can of worms you are talking about here.

So a Ukelele would be a..........