How to create Multiple types of account

I am making a placement management system ... So i need to create diff accounts for company ,students , admin with diff controls ...
So i should make diff webpages for everyone or anything else can be done..
and how do i recognize whether the user is admin company student

Try to add another field near each account in MySQL ,
Basically it should contain a number 0-9 or as many levels or usergroups you want , just name that field accesslevel or group.

Make sure on registration everyone enter to group "0" - regular registered members , than just play with the script and mysql , a script should read your mysql and if user's accesslevel is for example higher than 5 than its an administrator . something like that