• Assembly language is a low level language. It is dependent on the system architecture i.e. writing assembler routines for one computer, can’t be port to another computer without a radical rewrite of code. C is independent of system architecture. We can easily port C over various platforms quite easily.

• While writing assembly codes you get what you write. Every instruction is written as one mnemonic, one instruction to the processor and there is no optimization of code afterwards.

Example,
LOAD a

LOAD b

ADD a, b

STORE c //addition of 2 numbers

In C, each instruction/ line of code will result in may be dozens of instruction to the processor. Also the code will be optimized.

Example,

c = a + b //addition of 2 numbers

For C it is a 2 step process, first compiling and then linking it with libraries and other object files.