Char type is usually used to represent character data, such as letters, numbers, symbols, etc. In MCU, the char type usually occupies 1 byte (8 bits), and its data range is generally-128 to 127 or 0 to 255. Variables of type char are usually used to store a single character or string.
Int type is usually used to represent integer data, such as integers. In MCU, the size of int type is usually 2 bytes (16 bits), and its data range is generally -32768 to 32767 or 0 to 65535. Variables of type int are usually used to store integer data.
So the difference between char and int mainly lies in data range and function. In the C language of single chip microcomputer, char type is usually used to store character data, and int type is used to store integer data. It should be noted that char-type variables can be converted into int-type variables by forced type conversion (such as (int)ch), but it may lead to the loss of data accuracy.