In SQL, is UPDATE always faster than DELETE+INSERT?

Question

Say I have a simple table that has the following fields:

1. ID: int, autoincremental (identity), primary key
2. Name: varchar(50), unique, has unique index<

Answer 1

It depends on the product. A product could be implemented that (under the covers) converts all UPDATEs into a (transactionally wrapped) DELETE and INSERT. Provided the results are consistent with the UPDATE semantics.

I'm not saying I'm aware of any product that does this, but it's perfectly legal.