Decimal is also known as base-10 positional numeral system and occasionally used in standard system for denoting integer and non-integer numbers. Sometimes short form dec is used instead of decimal. In positional numeral system, contribution of each digit to the value of a number depends on its position in the numeral. In decimal system each decimal place is a power of ten.
Hexadecimal is also known as base 16 in computing and mathematics. In hexadecimal, numbers from 0-9 represents values zero to nine and alphabets from A-F represents values from 10 to 15. The plaintext is broken into two 4-bit values and represented by two hexadecimal digits. Hexadecimal is very popular due to its representation of binary-coded values. It is mostly used for computer system programmers and designers.