While a super-scalar CPU is typically also pipe-lined. Why pipe-lining and super-scalar execution are considered different performance enhancement techniques??
A superscalar processor can execute more than one instruction during a clock cycle by simultaneously dispatching multiple instructions to different execution units on the processor. Source: Wikipedia
Instruction pipelining attempts to keep every part of the processor busy with some instruction by dividing incoming instructions into a series of sequential steps (the eponymous "pipeline") performed by different processor units with different parts of instructions processed in parallel. Source: Wikipedia
Simply put, superscalar CPU executes few instruction in parallel (i.e. adds two pairs of numbers), while scalar CPU with pipeline executes different part of instructions in parallel (i.e. adds just one pair of numbers, but also decodes next instruction at the same time).