what is the difference between a saprophyte and saprotroph?

A Saprotroph  is an organism that gets its energy from non-living organic matter such as decaying pieces of plants or animals. For example; fungi, bacteria and protozoa. 

Saprophyte usually refers to these kind of plants, phyte usually means plant.  As no embryophytes (land plants) are true saprotrophs and Bacteria and fungi are no longer considered plants either. so the saprophyte is an older term and is not used now.