That being said what I find even more misleading is the fact that as a nominal interest rate increase credit increases.
This is the so-called Fisher Effect. You have to consider things upside down and, actually, the importance of money supply in the story.
"Credits" (here and there) stimulate demands (here and there) in the national economy. If supplies stay constant -- which it does empirically, at leasts temporarily --, markets will reach a new equilibrium via prices rising due to these stimulated demands, which generates inflation. Finally, higher inflation means higher nominal rates. Why? Because higher inflation (here and there) actually means higher (nominal) returns on equity (here and there). Incidentally, commercial banks (have to attract deposits and) will adjust their (saving) rates accordingly.
But remember that only reality matters when getting an idea of the "performance" of an economy.
Regarding your main question... The word "credit" as such, is used to describe the scriptural
ex-nihilo creation of money by commercial banks (and its debt counterpart). When the credit is reimbursed, the money is scripturally
Money demand, in contrast, can refer to any type of demand for money, be it stemming from final consumers, firms or even commercial banks themselves. Thus, money demand is conceptually a bigger set than that that we can associate to credits.