This comes from the confusion I had when first getting to grips with wireless blocks and bands and how they are all broken up.
It can be confusing but to keep it short and sweet here are a couple of things to consider:
The Manufacturer and Brand
Each have their own naming for how they have broken up the frequencies into blocks or bands so be sure when asking for frequencies in another country for instance you get the same block or band as your equipment
The range of the frequencies range from the recievers with larger number of frequencies within one block while the transmitters are often much shorter. When checking block and bands make sure if your transmitter and reciever are not on the same frequencies blocks that any others you rent in work within this range.
This is where the blocks and bands come from, bands of fequencies. The TV channels are some times sold off for other uses like with the 600MHz sell off for mobile internet.
Freq Block Checker
This is where you can check different manufacturers specs.
Let me know what you think down below in the comments: