Can someone explain the different relay schematics contact types?
There is a mesh in symbols because even manufacturer agree on a common language, marketing issues differentiate them frequently.

Even the common assosiation RELAY AND SWITCH INDUSTRY ASSOCIATION I think it is not existe anymore, but they are publish a handbook about relays, the "Engineer's Relay Handbook"

Bellow is en extract of the above handbook (5th edition) the types of contacs are available throught the market.