Pipit or Reed Bunting

I took this photo at Rainham Marshes on Sat 20-11-2021, sorry it's not that great. 

Can someone help with ID please? 

At first I thought it was a Pipit of some sort but on another website a few people have told me it's a Reed Bunting, I'd like to learn what the differences are so I'd be gratefull if someone could tell me what I'm looking for in order to come to that conclusion.

Many thanks.

Steve.