The classifying of Yeats' "Collected Poems" in its various editions is not an easy job, but mainly they can be divided into three groups.
1. Collected Poems, 1933. There were earlier collected editions called simply "Poems" (1895, 1905, 1910) but this one near the end of his life was the first intended as a career collection. However, it is not complete, as Yeats lived until 1939, publishing three more volumes of poetry; in addition "Last Poems" (which he had prepared) was published shortly after his death ("the day of his death was a cold, dark day"). Nonetheless, the incomplete 1933 Collected Poems is still with us -- the Wordsworth Poetry Series editions, usually issued as "Poetical Works" but sometimes called "Works of W.B. Yeats" or just "Collected Poems" -- but all bearing the same ISBN 1853264032, do not contain the full Collected Poems through 1939 but only the contents of the 1933 volume. These have been separated into their own entry with a clarifying if somewhat clunky title.
2. Collected Poems (1940 - ). This is the 'normal' Collected Poems, containing all the volumes of Yeats' poetry through 1939. From 1940 through the early 1980s (with very minor corrections, revisions and additions) this was the standard hardback Collected Poems of Yeats, and it continues to be standard paperback edition. These are generally called just "Collected Poems of W. B. Yeats"
3. Then in 1983 was issued the inaugural volume of "The Collected Works of W. B. Yeats" -- "Volume I: The Poems". This added to the 'normal' Collected Poems text 137 pages of previously uncollected poems, from magazines, letters, embedded in prose works, etc etc. When you buy the hardback Collected Poems of Yeats now, this is what you get (as noted above the paperback edition continues tp offer the 1940-1982 text). So, this greatly expanded edition has also been separated out and is entitled The Collected Works of W. B. Yeats: Volume I, The Poems.. It can be identified by the US isbn 0684839350 (9780684839356) or the UK isbn 0333353617.
Please try to place or combine your Collected Poems of Yeats with the proper edition.