When non-English people say they have been to England, they usually mean just London. When asked what they thought of their stay, the descriptors "expensive", "bad-tasting food" and "unfriendly people" burst forth. These were exactly what I had thought 8 years ago after my summer stint oafing around London. But let's take a look at these typical descriptions of "England": it was expensive because at the time the currency conversion for $1 was about 50p and it was London, CENTRAL LONDON. You're looking at £4 (applying my currency conversion: $8) for a pint whereas the outskirts provide pints for less; bad tasting food was mainly because I didn't know where to go and having little money because of the "expensiveness" of it all, I happened to eat bad tasting food (and I would have also described the food as small portioned). And the unfriendly people--The general difference between Americans and the English when it comes to making friends is that Americans are initially friendly, will try you out as a friend and then if all goes wrong, slowly ignore you; whereas with the English, it becomes an epic amount of time before they warm up to you and then consider you as a friend.
The persistent stereotype of "unfriendliness" toward the English has led me to discover that this is a generalisation because it is also used by the Northern England to describe its Southern counterpart. Since most non-English visitors believe they have a good sense of what England is about through observations of London life, this inter-English stereotyping may be new to them. Northerners (e.g., they might hail from Newcastle, Manchester or Liverpool) are seen as more sincere, direct and friendlier than Southerners (e.g., coming from places like London, Oxford, Essex). But the Northerner's impression of a Southern? Arrogant, rude and two-faced. For Southerners, they are seen as more affluent, intelligent and sophisticated than Northerners, while their impression of Northerners are ragged dressed specimens from drug and poverty infested lands who think orange tans and mini-skirts in the dead of winter are fashionable.
These differences between the English North and South are an example of just how complex and layered generalising is: generalisations from outsiders, from insiders and even from each other. Beyond England, other North/South "divides" also exist: In California, the NorCal/SoCal divide pits cultured and intellectual Northerners against trendy and beach-loving Southerners; In Italy, it's the time-efficient North versus the leisurely paced South. These differences highlight how one context--anywhere--is not as homogenous as someone would like to believe. In generalising, it is a way for the mind to cope with the multitude of observations and experiences processed on a day-to-day basis. We want to know with certainty that this is how we expect particular things to be and by compressing our outside interactions into a generalisation, we provide an immediate reference for ourselves for future interactions. Just as generalisations are not absolutes and destructive if taken seriously, they help with organising the world around us in an understandable form. It is a way to cope with differences and to superficially understand them.
So back to the original question: there are differences to some extent. From my own experiences, Northerners tend to be more frank and friendlier than Southerners. They are not afraid to express their opinions packaged in a no-fuss and direct way. Accents aside, on the tube, Northerners are easily spotted by the way they begin conversation with strangers or make remarks aloud. Interestingly, Southerners will tell me that there are no real differences between them while Northerners will say otherwise.