ASCII
This is a representation system for all characters in the English language with 128 individual possibilities; containing all the letters including the capital versions ECT. Each character is stored using seven bits. ASCII isn't compatible with any other languages. For example, a device only capable of reading ASCII can't read other languages, but a device using the more universal data type uni code, can read ASCII

Uni code
This is a representation system for all characters in all languages. This uses 8 bit for each character and uses two bytes. This system can represent up to 65536 characters. Unicode is backwards compatible with the ASCII system, the first 256 of the characters are the same.