The difference between oil, absolutes and extracts is how they're extracted from the vanilla pod. I haven't smelled absolutes or extracts, but from what I've read most people say that this form of vanilla doesn't actually smell that good. It smells good when a perfumer blends it, etc. Essential Oil, of course, is a marketing term - probably means the company blended the vanilla (absolute or extract or a synthetic replication) with some other note in oil. Since your nose is not trained enough to be able to detect whether you're being ripped off (they might charge you for absolute and sell you a cheaper synthetic recreation of vanilla absolute), I would just stick with an Essential oil for the best smelling product to use the way you want.
If it's being sold as an essential oil it's probably already diluted for skin application. If it is an absolute or extract, it MUST be diluted in oil before skin application - you can seriously damage your skin if you put it on full strength. Be careful.