Since my son is only 4 and its hard for me to get help for him is there any way I can tell that he has aggrisive adhd?

You certainly can. By staying calm. Overreacting to your child's behavior or response to ur command isn't going to get u anywhere. They will overreact and become"defiant " and it will escalate and get into your nerves now making you angrier and mad. Therefore nothing accomplished only fuming parent. Conclusion adhd, defiant kid, brat , whatever you call it. Talk to them calmly and make it a game and fun. Shd work!
Not really a type. There isn't really anything known as 'aggressive adhd' but there are other disruptive behavior disorders like oppositional defiant d/o. Have you discussed your concerns with his doctor? A helpful e-book for you on kindle is called: parenting the kids according to a child psychiatrist. For a good dvd on amazon, check out: the 20 minute behavioral miracle. Good luck.
School evaluation. You can have him evaluated by the local school district- they are required to evaluate any child over 3 years old who seems to have a learning problem. Request it in writing to the principal of your elementary school or call the local early childhood intervention services. 4 years old is young for adhd medication, but he may need some behavioral therapy to help him control his behavior.
Firm love. At that age children are testing to see what they can get away with. They need consistent firm love and direction. Behavioral management is best and avoid use of medications. Often they are worse with mothers and angels with others.