Some things to note on the third picture are the white breast (without yellowish tone) and the white outer tail feathers. Mistle Thrushes can show arrow shaped spots, particularly on the upper breast, but in general the spots are more rounded than Song Thrush, particularly on the belly and flanks.
The single most obvious feature is the upperparts colour: mistle thrush is normally distinctly greyish, song thrush clearly brown. Mistle thrush is a longer-looking bird, with a (relatively) smaller head.
Another pointer that you won’t find in the guides testoduro, is that the spotting on the chest of Mistle Thrush is vertical until you reach the lower belly whereupon the lozenge shape becomes horizontal.