There is only one difference, i.e., in the 'nous' form ER ending verbs add 'ons' to the main verb, but in the GER ending verbs 'eons' is added. Like
Nous parlons, aimons, etc
Nous mangEons, nagEons, etc.
1 5 1
there is an exception that an 'e' is added before ons in the 1st person plural which is nous. the rest are conjugated as er verbs.
The only difference between er and ger ending verbs are that they end with eons in nous instead of ons
hope u understand