This question is asked very frequently, by people wanting to cash in their Bark Modules. Try searching Google (not the forum search function) and you will find many threads:
The short version is: These are extremely different guns --- about as different as two guns can be. Polaris/Supernova is really a crowd-control tool. The damage is decent. Your teammates may dislike the high knockback, so use it carefully. Biohazard/Neutralizer is a really strange and fun weapon, which can do great damage. Your teammates may kill the enemy before you get a chance to, though.
This question is asked very frequently, by people wanting to cash in their Bark Modules. Try searching Google (not the forum search function) and you will find many threads:
http://www.google.com/search?q=spiral+knights+forum+pulsar+catalyzer
The short version is: These are extremely different guns --- about as different as two guns can be. Polaris/Supernova is really a crowd-control tool. The damage is decent. Your teammates may dislike the high knockback, so use it carefully. Biohazard/Neutralizer is a really strange and fun weapon, which can do great damage. Your teammates may kill the enemy before you get a chance to, though.