aggressive puppy

Cali just turned 5 months a couple of days ago and got all her vaccinations and deworming and etc, no infections, no sicknesses, perfectly healthy so I know she's not acting out because she's feeling bad. I walk her two times a day minimum, though usually a quick walk/play time in the yard...

Kaiser just turned 4 months this week, so I know he's still a young puppy, but we're concerned about how aggressive he seems. We are first-time dog owners so everything is ‎new to us but his behaviour doesn't seem to strike us as normal puppy behaviour. We were finally able to stop his play...