BTO Garden BirdWatch - Telling apart Coal Tit and Marsh Tit

There are two graze tips that frequently occur in gardens, coal tit and marsh tit, but how do we tell them apart? Coal tit is slightly smaller than blue tit, has a black cap and a white stripe running down the back of the head, has white cheeks and a large obvious black bib on the throat and two narrow white wing bars. Marsh tit is slightly larger than blue tit, has a black cap that runs down the back of the head, no white stripe, white cheeks and a small neat black bib that isn't at all obvious and plain wings. The calls differ too. Coal tit utters a slurry and marsh tit a sneezy.