Serovar vs Serotype (Type vs Prid property)


While looking at Salmonella sp, I came across these 2 tests:

Code LongName Property
20951-0 Salmonella sp serotype [Identifier] in Isolate by Agglutination Prid
65756-9 Salmonella sp serovar [Type] in Isolate Type

Why are the properties different (Prid and Type, respectively)? What is the meaning of the Type property?