never watched DBZ so all i know of SSJ is that they go blonde and become more powerful
and in that sense its equivalent to super sonic, and its super silly, and it owns
what do the different levels look like?
SSJ1 is the blonde hair.
SSJ2 on some looks exactly the same hair style wise, but on others look different. Gohan's SSJ2 hair is different than his SSJ1 hair, but Goku's is exactly the same. The main difference is there's electricity around the person.
SSJ3 their hair grows longer and they lose their eyebrows.
SSJ4 is tied to their Oozaru form, or their Great Ape form. They become hairier all over their body and that's the main difference.
Super Saiyan God they have a slimmer body/ red hair/eyes.
SSB or Super saiyan God super saiyan, they get Blue hair/ eyes.
Legendary Super Saiyan they get Green hair. Only two people in the series have been able to achieve this form.
Every SSJ form besides the Legendary form is a multiplier, so just having hte forms isn't enough, you have to have a strong power level without the SSJ forms for the SSJ forms to be multiplied enough to be of value.
There's also Ultra Instinct/ Gohan Beast, but it's unclear if tehy're technically super saiyan forms, as one is when you learn to dodge and attack without thinking/ the other one is a buff to Gohan's Ultimate form which isn't a SSJ form.