Base-10 (also called decimal) number system uses ten symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.
Base-24 number system uses 24 symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 'A to N' (or alternatively 'a to n').