what's difference between Maya and Blender?
Hum. Depends... With both of them you can do awesome stuff or lame projects.
As with a lot of applications one defining thing on which application you need to use is the context of where you are doing it. If your work environment requires one application or the other.
If you are a freelancer and you want to go that way, Blender is a great choice, it is free, and will remain free, so you can do projects and collaborate with a lot of freelancers. It is quite powerful, and very, very light on the basic specs needed.
If you plan to work as an employee on a company that uses Maya (or you want to be a studio that interacts with other studios that does) you could use it, but the licence is not cheap. But you can have a 3 year free licence as a student. http://www.autodesk.mx/education/free-software/maya So go and test it. The specs needed are higher.
Maya is used more often by large studios, but a lot of professional projects are done too in Blender.
So it is an opinion based choice.
Should I switch?
No idea. Download it and find out.
If you wanted a technical comparison... you probably will not find it.
There are several modelling methods, different interfaces and ways to do things.