What is the difference between a solid state relay and a semiconductor contactor?
Can both switch ac loads? This a link to a company that distinguishes between the two.

http://library.abb.com/global/scot/scot209.nsf/veritydisplay/da7ec357f6a7461cc12573ad004e1e83/$File/2CDC110004C0205_07.pdf

 

If they are designed to switch AC loads then they can do it. Solid state relays use transistors and thyristors (TRIACs) to make the switching whereas contact relays use moving contacts.

 

A contactor is a heavy duty relay. This is also true for solid state versions.
This definition seems to be at odds with the link that you posted.