Autism or phase

I have a 3 year old boy his behavior is not normal to me my husband and his father he slaps and punches things in sight and his tantrums get progressively worse each time and spits constantly for no reason and won't communicate with my husband unless I'm not around and is plain mean to my baby9 months old who does nothing but love his older brother his older brother will run away from him when I'm around and if I'm sitting down he will get on my shoulders and wine like no tomorrow