| Novorapid (or Novolog as it's also known in some places) is pretty much identical to Humalog, but as has already been mentioned, it has perhaps a slightly more aggressive action profile.
However, as far as I'm concerned, the real difference is in the insulin pens. Novo Nordisk seem to be the only insulin manufacturer that has pens that are made of steel as opposed to being plasticy, easily breakable things. The Lilly pens are also huge as well - they're the same length as the Novopen but considerably wider. If you're using insulin pens then you may want to take these things into account when choosing your insulin type. Since I carry my pens everywhere with me, portability and pocket space are something of a must, and providing I can get that without trading off my control, then that's the deal-breaker for me. | 
