are some nokia chargers different?

the one at home that came with my 5800 seems to charge the phone up in under an hour.

but the one at work that came with some other phone, takes what seems like all day to charge the same phone?

The older charger (which looks chunkier and has 7X in the model number) are a lot slower than the newer 8X slimmer model. I use a 7X (left over from my previous phone) in the bedroom to charge overnight and an 8X downstairs for fast charging.