What do the thrush and the poet have in common in "The Darkling Thrush"?

To be honest, it is the differences between the thrush and
the poet that is the point of this excellent poem. However, both the thrush and the
speaker are presented as being alone in an otherwise desolate landscape. There are no
other forms of life present except for the poet, leaning upon his "coppice gate" and the
thrush singing joyfully in spite of the desolation around him. Likewise, the physical
description of the thrush seems to match the spiritual or internal description of the
speaker. Note how the thrush is described:

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An aged thrush, frail, gaunt, and
small,

In blast-beruffled
plume...

The emphasis on the
frail nature of the bird perhaps is echoed by the pessimism of the speaker in this poem,
who, like the thrush, finds himself "gaunt" and "small" and "beruffled" when faced with
the bleakness of the world and of the created
order.

However, the essential difference is that the thrush
is able to sing and find some evidence of hope in what he sees, whereas the speaker is
not.