he major differences between Adware and Spyware is:

a$.$

Adware is more dangerous than Spyware, therefore keylogger is a an adware

b$.$

Both of adware and spyware are a type of social engineering and they are not dangerous

c$.$

Adware is another type of viruses

d$.$

Spyware is more dangerous than Adware, therefore keylogger is a spyware