Final answer:
Pairwise alignment compares two sequences to find the best match, while single alignment compares a sequence to multiple others to find conserved regions. Pairwise alignment is fast and used to identify similarity, while single alignment is slower and used for studying evolutionary relatedness.
Step-by-step explanation:
Pairwise alignment is the process of comparing two sequences to find the best way to match them. It is used to identify regions of similarity between biological sequences like DNA, RNA, or proteins. Pairwise alignment focuses on finding the best overall alignment between two sequences by optimizing a scoring function that takes into account matches, mismatches, and gaps.
On the other hand, single alignment, also known as multiple sequence alignment, compares a sequence of interest to multiple other sequences. It is used to find regions that are conserved across different species and can be used to construct phylogenetic trees. Single alignment is slower than pairwise alignment, but it is useful when studying evolutionary relatedness.