When looking at the differences between single and album covers, there is often some correlation between the two but differs from artist to artist.

The Arctic Monkeys first single was 'I bet you look good on the dancefloor' released on Domino records, the cover of the single depicts a young woman who is a 'trainee' shopkeeper of a connivence store as you can see from the badge on the apron.
You can also see that she is handling some items that you find in a convenience store accompanied by the alcohol shelves behind her and the sign also behind her stating that tobacco products cannot be sold to anyone under the age of 16 which was a law that was abolished in 2007 and changed to 18 years of age.
The video to this single has no relevance to the single cover as it is a live performance shot in a small studio to a small crowd using television cameras from the 1970's to give the video a retro look.
Some would say the photo on the cover correlates between the fact the song is talking about a woman on a night out but that isnt intentional

The album that this single featured on was 'Whatever people say i am, That's what im not'. This album has a photo of Chris Mcure on the front smoking a cigarette that was taken in the early hours of the morning in a Korova bar, Liverpool. This photo was one take in the moment with no planning, its a simple yet effective approach that somehow correlates to the band themselves, connoting an indie type scene/genre using the saturated colour look on the photo. The photo alone has absolutely no relevance to any song on the album in particular and has no intentional relevance to the style of the band.
The house style of the two albums is about as far a the correlation between the two go, the 'Arctic Monkeys' logo at a sort of 15 degree angle that is stamped on the front of both the covers.
On the front cover of Calvin Harris' 'Feel So Close' single there is a picure of a western cowboy with a white horse, that relates directly to the music video for the song where there is a narrative of the same man with his horse. Its an effective approach to the simplistic style of the genre of music, a shot taken from the production of the music video, it also makes the marketing of the video a lot easier as the general public will recognise the photo and relate it back to the video.
This is the album in which 'Feel so Close' was released on, as you can see there is the same sort of house style from the american suburbs but the album bares no relation the video from one of the songs on the album.
It shows the artist sitting on a curb in an american style street with his name and album names pictured on the wall behind him.

This is the single cover for the single Inhaler by Foals, the cover this is related soley to the video for inhaler as you can see the jacket that he is wearing on the cover is the same one that he wears in the video for inhaler, this creates a direct link between the two rendering it a single cover.
The album cover that this single is on is completely different on the other hand its a retro style photo of horses in the sea which bears no relevance to the album title at all and is not related to the songs on the album either, this shows that the main thing behind the album covers is that its down to photography rather than relating the album cover.
This is something that we should look further into to gauge how well albums relate to the album content.