A teaser is often associated with a pole and clear plastic stilettos :)
All tasers are stun guns but not all stun guns are tasers.
A taser has a cartridge that attaches the barbs into a suspect so that he can't run away. If you remove the cartridge, you get a stun gun which can zap the attacker with something like 50,000 volts of power. If you shoot and miss the attacker with the taser, you can use the stun gun. If you are going to buy one for self-defense, go for the taser.
All tasers are stun guns but not all stun guns are tasers.
A taser has a cartridge that attaches the barbs into a suspect so that he can't run away. If you remove the cartridge, you get a stun gun which can zap the attacker with something like 50,000 volts of power. If you shoot and miss the attacker with the taser, you can use the stun gun. If you are going to buy one for self-defense, go for the taser.