へ and に there is no difference. They can both be used and are considered interchangeable. I see both に and へ in writing and talking.
えきにいきます。- I'm going to the train station.
へ can replace に and vice versa.
In theory へ is for movement in a direction, while に implies arrival at a specific destination. [or some such]. In practise there is very little difference.
also used as a shortcut in email as in DCへ ->this part is to DC:
? it would be nice to get an explanation of difference between ni and he. ロンドンに行く＝ロンドンへ行く ロンドンでお会いしましょう？
"In motion constructions -ni and -e appear to have the same distribution [...]. The primary difference in distribution is that -ni may occur in other verbal contexts, as I show below, but -e may not, while -e may appear marking arguments in nominal constructions but -ni may not, [...]"
N = noun
Note: Apart from the DCへ letter / email addressing type usage you can't use へ to indicate going to a person. e.g. (BAD) DCへ行きました。[DC he ikimashita] I went to DC. (GOOD) DCの家へ行きました。[DC no ie he ikimashita] I went to DC's house.
I'd get rid of the above 'bad' example, because DC is also a place (Washington DC), in which case you CAN say "DCへ行きました。" Put some other person's name in that to make your point, and then please delete this comment :)