What is the difference between Onkyo 3 series and 4 series

[siddh]

Guys need help here,

Can somebody tell me what is the difference between 3 series and 4 series. When i see the models i see numbers like 3300 3305 5300 9300 and 4 series like 3400 3405 5405 9405 etc. Is it just a number or something specific?

Thanks,
Sid.

 

[baijuxavior]

I think the 4 series is a newer version.