Picking the right monitor can be a real challenge. If you’re building a computer, something like a hard drive is pretty easy to understand, you have to worry about different interfaces or form factors, but specs like storage space or transfer speed are pretty reliable, and comparable. That is to say, if you bought two hard drives advertising a terabyte of storage, it would be a real surprise if one of them actually was only half that big.
Monitors can be a bit more tricky. Response time, how quickly a pixel can change color, in particular, is pretty subjective, and the times manufacturers advertise can’t really be compared between different monitors. It wasn’t always this way, response time used to be measured with a defined standard, but that practice fell out of favor as faster (and less standardized) measurements became popular.