EX3300 has better specs as it can do BGP and routing-instances with the right licenses. This is not found on the EX2300.
Depending on port usage they are pretty close in price to each other when doing VC on 24 ports models:
EX3300-24T: 3200 USD list
EX2300-24T-VC: 3150 USD list
Price difference is a bit bugger on 48 ports models:
EX2300-48T-VC: 4200 USD list
EX3300-48T: 5095 USD list
There are not licenses for ports on either on the platforms. You have the 4 x SFP+ port available when buying the switches.