BTW, starting in late-67 and 1968 the match-ups get more complicated (and probably more arbitrary), in large part because the music of both bands changed quite a bit and became even harder to compare with each other.
Generally I've been comparing Rubber Soul songs to Pet Sounds songs, and Revolver/Sgt Pepper songs to Smile session songs (Smile having almost enough material to be a double album, even though it wasn't intended to be). Though I've got a Wild Honey song against a MMT song above, generally for the rest I'll be matching the following albums. But there will be exceptions.
Wild Honey & Friends vs 'White Album'
Let It Be vs 20/20
Abbey Road vs Sunflower
The White Album is a double album, so might as well compare its songs to 2 BB albums (just as I compared Smile to 2 Beatles albums). Wild Honey is late 1967 and Friends is early '68, while the White Album was recorded in May-Oct 1968, so the timings there are pretty close.
Let It Be was actually recorded (mostly) prior to Abbey Road even though it was released last. I'm more interested in the timing of the two bands' creative impulses, which is why I've been focusing on recording dates instead of release dates. The only Let It Be song recorded in '68 was Across the Universe; the rest was mostly recorded in 1969 with some early 1970. So it seems more fair to compare it to the BB 1969 album 20/20.
Sunflower was recorded in a wide swath of 1969 and 1970. Abbey Road was recorded Feb-Aug 1969. So those two have a pretty good overlap.
I won't count "Yellow Submarine" which only had a few new & original tracks on it. But then, I didn't count "Beach Boys Party!" either.
Since the Beatles broke up after Sunflower & Abbey Road were recorded it would be unfair to compare later BB albums to a Beatles album.