Major difference
1. TRP : target rating points.
It varies on given parameters barc releases its to its subscribers in +2 , +5 and +13 age group. Where they target particular age group.
It normally indicates the total veiwership of show and channel
2. GRP : gross rating points.
It is the average rating point given to a channel not for shows. It normally divides impression of channel on a particular period by product of no. Of days and population of TV.
3. TVR : telivision rating point.
It's the average points given to shows on basis of impression. It decides the how viewers are tuning in.
4. VER : veiwer engagement read
It is similar to tvr that's where similarities end. It reads how viewers are engaged on a particular shows. This counts weather viewers change channel during ad break. Or weather they watch complete episode or do they watch few clips. This helps advertising agency to keep track of their ad reach