A set of basic questions about mysql

[Rodolfo Aramayo]

Dear Ryan,

MacPorts has nine mysql5-related ports:

mysql5 @5.1.63 (databases)
mysql5-devel @5.5.2-m2 (databases)

mysql5-server @5.1.63 (databases)
mysql5-server-devel @5.5.2-m2 (databases)

mysql51 @5.1.63 (databases)
mysql51-server @5.1.63 (databases)

mysql55 @5.5.25 (databases)
mysql55-server @5.5.25 (databases)
and
ocaml-mysql @1.0.4 (databases, devel, ml)

I understand the difference between mysql5 @5.1.63 and mysql5-devel @5.5.2-m2
What is the difference between mysql5 @5.1.63  and mysql5-server @5.1.63?
I am also am not sure I understand the difference between mysql5
@5.1.63, mysql51 @5.1.63 and mysql55 @5.5.25 ?
When does one uses mysql5 versus mysql5-server?

Thanks and keep up the good work

--R