Separating adult Tree and Meadow Pipits

If only Tree Pipits stuck to trees, and Meadow Pipits to moors and meadows their identification would be easy. Fortunately only the Meadow Pipit is likely to be encountered on the open moors but around the fringes the Meadow Pipit may be found in trees and bushes and the Tree Pipit spends a fair bit of time feeding on the ground where Meadow Pipits may also be found.
The Tree Pipit is a true migrant leaving the local area in September for sub-Saharan Africa and returning in mid-April. Most of our Meadow Pipits are also migrants heading to southern France and Iberia but a small number remain throughout the winter, usually in low land meadows, with the bulk returning, and many passing through the area, from mid-March through April.
In spring and summer their songs are the easiest way to separate them and the Chaffinch like rattle of Tree which usually precedes the zee-zee-zee phrase as the bird parachutes back on to a tree are often the first indications that Tree Pipits have returned to the local forestry clearings. The Meadow Pipit song is also given in flight with rising tinkling notes followed by a trill as it descends back to land.

Tree Pipit (left) v Meadow Pipit (right)

In direct comparison the Tree is a longer slimmer bird than the Meadow and has a stouter thicker based bill but this is difficult to judge when faced with a lone bird. In general colouration the Tree is a paler, brighter looking bird with warmer brown tones and whiter underparts compared with the more olive brown tones of Meadow. In a close view the short curved hind claw of Tree  is diagnostic, Meadow has a much longer less curved hind claw. 
The single most important plumage characteristic is the flank streaking which is fine on Tree and can be almost invisible at a distance so the pale lower breast contrasts with the dark streaking of the upper breast whereas on Meadow the broad dark streaks of the upper breast continue down the flanks.
On the upper breast the dark malar stripe of Meadow tends to coalesce into a dark splodge on Meadow below the cheek, which is absent in Tree.
The pale tips to the median coverts contrast with the dark feather centres on tree giving a distinct black and white bar on the wing which is more subdued and less contrasting in Meadow but lighting can affect this, on a dull overcast day the Tree looks less contrasty than in bright sunlight.

Tree Pipit (left) in subdued light v Meadow Pipit (right) in bright light

Tree Pipit has a pale supercilium, most obvious behind the eye and often shows a pale spot on the ear coverts similar to the much rarer Olive-backed Pipit. On Meadow the supercilium is indistinct producing a rather bland head pattern where the most noticeable feature is the pale eye ring.

The Meadow Pipit will often call when disturbed giving a distinctive sip-sip-sip whereas the Tree tends not to call much on the breeding grounds but delivers a characteristic rasping seep call on migration.

Behaviour wise, other than habitat preferences mentioned at the start of this post the Tree Pipit has a tendency to wag its tail when moving in a tree which is not something I've seen the Meadow Pipit do which tend to remain stationary having  landed in a tree or bush.