Let It Be's easier to explain. This was the Beatles au natural. That was a concept - simply a soundtrack of them working together. This was not a scripted effort. It was spontaneous. Indeed, this lp was a concept in the sense, too, that it was the accompaniment to an unscripted film. That was a concept & I think it was unique and groundbreaking for the time.
The White Album is a motley collection of Beatles songs. John Lennon referred to it as an effort on which they all played, but not necessarily together. The White Album itself was blank - that was a concept. Nothing was deemed appropriate to describe the contents therein. That was, arguably, a concept, a purely abstract one at that. It's harder to explain and I guess I could aspire to defend my position more thoroughly. I've also believed there was some thematic content to the songs. Perhaps, I'll save that for a later paper as I do have further ideas upon this subject. This would be worthy of a more devoted effort.
Hope this elucidates even if weakly so.