Full Idea
Two things are said to be type-identical when they are similar enough to be declared qualitatively identical.
Gist of Idea
Type-identity is close similarity in qualities
Source
Colin McGinn (Logical Properties [2000], Ch.1)
Book Reference
McGinn,Colin: 'Logical Properties' [OUP 2003], p.2
A Reaction
A simple point which brings out the fact that type-identity is unlikely to be any sort of true identity (unless there is absolutely no different at all between two electrons, say).