A differential pressure can be measured between two points on independent systems or between two different points on the same system.
The main use for a differential pressure sensor is to measure the difference in fluid or gas pressure across a restriction in a pipe. The flow can then be...
Don't know about those 2, can't recall seeing them before. Don't know if it's any help but Plumb Center had a pack of 2 Myson pumps on offer about 60 quid.