A charitable loan is loan lent to the poor. Interests cannot be demanded on them. The loan is charitable (Exo.22:25)
A commercial loan is a loan that someone takes in order to invest it into property or business. The money is expected to multiply through such investment and accrue profit. Interest rates are applicable to such loans.
A luxury loan is loan taken in order to purchase things of luxury, not things of need (e.g. HDTV, Cars, etc). Usually, the goods purchased there by either get used up (eaten up) or fall into depreciation, other conditions remaining the same.
All loan involves some surety or collateral of some kind, in proportion to which faith and value the loan is lent.
The Bible prohibits staying in debt (Rom.13:8) and not returning what is due to the other (Psa.37:21).
In the Old Testament, failure to repay could end one up in slavery (Deuteronomy 15:12-18).
However, the Bible does encourage charitable loans. In fact, in the New Testament, the rule is intense: one ought not to expect a return, especially if the loan was to aid the poor (Matt.5:42; Luke 14:12-14). However, Jesus showed that it is not unwise to lend to bankers (investors) who could multiply the money and repay it with interest (Matt.25:26).
Usury, Interet, and Loans (Gary North)
Ten Principles on Money for All Full-Time Workers (Zac Poonen)
Few Principles of Financial Prosperity (Marbaniang)