Centrifugal pumps can be grouped into several types based on the compliance with industry standards. some of these groups alongwith governing standards are mentioned below:
1) ANSI Pump - ASME B 73.1 Specifications
2) API pump - API 610 Specifications
3) DIN pump - DIN 24256 Specifications
4) ISO Pump - ISO 2858, 5199 Specifications
5) Nuclear Pump - ASME Specifications
6) UL/FM pump - NFPA Specifications
You can refer to these codes to find out a typical general arrangement drawing for each category of pumps to find out differences in the pump appearances.
one difference i can tell you:
API Pumps are pedestal mounted and thus give room for vertical thermal expansion. ANSI Pumps are foot mounted usually and hence there is no room for thermal expansion. this is an important consideration while selection of a pump in high temperature region.