“I am newly experienced and cannot quite bring myself to ask my girlfriend (she is more experienced than I am) the following questions. Can a girl tell the difference when her guy is/is not wearing a condom? Does it make a difference to her? Can she tell a difference when he cums and is/is not wearing a condom? Does it matter?“
Though I suspect that most women can feel the difference between bareback and a rubber clad gent (like me), I think whether it “makes a difference to her” will depend on the girl.
Women who want to make sure that they aren’t going to get pregnant or catch anything icky from a male partner may tell you that it DOES make a difference to them because they would rather be safe than sorry. And if they are sensitive enough to tell when you aren’t wearing a rubber or when it has broken, they will (or at least should) boot you out ASAP.
However, a woman in a long-term, monogamous relationship, where both partners have been tested, and where alternative (and trustworthy) forms of birth control are being used, might opt for a bareback ride because it can offer more stimulation than the average condom (though not more than some of those neat textured condoms).
Once again, not all women can feel a difference when a male partner finishes in a rubber or not, but some women do prefer the rubber finish – since it’s much easier for clean-up and is safer (as I mentioned above).
And finally – does it matter? Well it all depends, are you trying to find an excuse not to wear a condom? If so, I don’t think you should try to slip one past her, since, if it were me, you’d be in a lot of trouble. Other than that, see my answer to the first part of your question – it’s about personal preferences and how safe you’d both like to be.