I own the Q and the Q7 and use them interchangeably.
If I spent a lot of time exhaustively evaluating both cameras the Q may be just a smidgen better built. Since I don't, they feel the same to me when I am using them.
Likewise, if I spent a lot of time pixel peeping the images that come from both cameras I may discover that the Q7 provides a smidgen better image quality. But I rarely pixel peep anything, and we are talking about miniature cameras with miniature sensors.
I am far more interested in the fact that either camera will produce stunningly beautiful prints using a form factor that makes most DSLR cameras look like monsters.
I am pretty sure you will enjoy whichever Q you decide to buy. After all, they are the best miniature photography system available anywhere. Perhaps even the best camera system available irregardless of size.
EDIT - To clarify, "smidgen" is the scientific term for just about anything that is just barely more than the other, but very difficult to measure accurately.