Totally different like everybody is saying. IV coke is a rush, that's it. An incredible, awesome, euphoric, ear-ringing, heart-pounding, vision-blurring, mouth-numbing rocket ride. It is instant and, if you manage to hit that certain dose, lasts for about 5 minutes and winds down over the next 10. If you DON'T manage to hit that dose (~100mg of pure, lab-grade hcl for me [anywhere from 100-200mg street coke]) it will last about 20 seconds, fade uncomfortably fast and leave you jittery, cranky and utterly unsatisfied.
Snorting it is euphoric and stimulating but I don't get any sort of rush and the side-effects are a lot more drawn-out.