If you can actually imagine a red wheel barrow,1 we'll grant you all the rest.
When one says that a great deal depends on such and such an image, of course that does not mean that other images wouldn't be adequate too; the natural object is always the adequate symbol. But each may be as dull as any other. (On this a curious remark by E. Pound.)
To get into the correspondences between the Tractatus and Spring and All, published in 1922 (in English) and 1923 respectively, let's start with Chapter XXII of the latter, which (after the famous red wheel barrow) begins with the following remark:
The fixed categories into which life is divided must always hold. These things are normal — essential to every activity. But they exist — but not as dead dissections.
The opening gestures of the Tractatus of course spring immediately to mind:
1. The world is everything that is the case.
1.1 The world is the totality of facts, not of things.
1.11 The world is determined by the facts, and by their being all the facts.
1.2 The world divides into facts.
The crucial difference in outlook of the two books, which we can label simply "poetic" and "philosophical", is here captured by Williams's focus on "activity" and Wittgenstein's focus on "facts". Facts are to philosophy what acts are to poetry. Both, however, are emphatic about how "essential" all this is: Williams already in the quoted paragraph and, of course, in that iconic opening stanza "so much depends/ upon", Wittgenstein at 2.011, saying, "It is essential to things that they should be possible constituents of states of affairs."
This is a good beginning.
1The cleverness of this bit will be lost on anyone not familiar with the opening remark of Wittgenstein's On Certainty, Chapter XXII of Williams's Spring and All, and Ezra Pound's "A Few Don'ts by an Imagiste". Even this footnote is thus clever.