The first and the main difference between these two number systems is the base value. The Binary Number System has a base value of two (2), while the Decimal Number System has a base value of ten (10). That means that each number has a different value in these two numbering systems.
The Binary Number System is used in computer systems and digital devices. While for humans, the decimal number system is understandable. So to convert the computer instructions to human-readable instructions, binary to decimal conversion is essential.