Pump ratings are something of an illusion, which is to say they are often manipulated in order to fulfill marketing hype requirements. Various attempts have been made to standardize things, but the big obvious advertised HP number remains controlled more by marketing than by reality.
First there is the rated HP, the number they advertise. This number gives you a vague idea of how large the motor is, but doesn't really mean much of anything. Then there is the SF, or service factor, which you should be able to find but which is not always listed very prominently. HP * SF, sometimes called SFHP or brake HP, gives you the true HP number that can be compared between vendors.
Full rated, max rated, and up rated are terms that have been invented to hint at what the SF number is. Full rated pumps tend to have SF between 1.5 and 2, while up and max rated pumps tend to have SF between 0.9 and 1.2. However, there is no definite relationship between the terms and the SF numbers, just a hint. Different manufacturers use the terms in different ways.
The number you really want is SFHP.
Of course there is one more bit of complexity beyond that. The SFHP tells you how powerful the motor is, but it doesn't tell you how good the pump is at turning that power into water movement. Some pumps are better at that then others. But that is a project for another day.
