Stop tap and stop cock

[gcol]

What's the difference between a "stop tap" and a "stop cock"?
It's just I was flicking through screwfix and they have both. They look the same thing except the stop cocks are cheaper.

 

[Nige F]

Like a cock `n` en

 

[gcol]

Anybody? I'm confused.

 

[ChrisR]

Semantics. Peglers are a bit dearer, usually a bit better quality, if only in the QC.