Tek's post #4 puts the picture in the correct perspective. Capitol in the US tweaked around with the sound for all the early releases to make them sound (to them) more radio friendly. This doctored sound is significantly different from the Parlophone mixes. All the Beatles tracks were recorded in Stereo - 2 and 4 track initially - before being mixed down to Mono. The original Mono mixes were carefully crafted under direct supervision from John and Paul - they left the stereo mixes to the Parlophone engineers. This was because they considered Mono to be more important back then, as the majority of music lovers in Britain - then still economically well behind the USA- had Mono systems only. Stereo systems, in Britain, only started getting market share in the late 60s, when the economic climate started to improve.
The Beatles, also, did not believe in shortchanging their customers - they issued many songs as Singles only, and those titles were not included in the Albums. (Which is why it is worthwhile to get the two 'Past Masters' collections - they compile all the early Singles)
In America, Capitol included Singles into the Album track listings,, and they also changed the original sequencing. Most Parlophone LPs up to Revolver had 14 tracks, while the Capitol issues has just 10 or 11.
The album titles were also different: In the UK, you had Please Please Me, With the Beatles, A Hard Day's Night, Beatles for Sale, Help, Rubber Soul and Revolver.
In the US, it was Meet the Beatles, The Beatles Second album, Something Else, The Early Beatles, Beatles VI, and so on.
It was only from Sgt. Pepper onwards, that the Parlophone and Capitol releases had the same titles and the same song listings, though there again the Parlophones still sound much better. One exception: Magical Mystery Tour was released as a double EP in the UK, but Capitol released itas an LP by cobbling together a few additional singles.
John Lennon famously once said: 'Listen to Sgt.Pepper in Mono, it's the real deal'.