They are different variants but the bases on them are the same, the ESB will have zero t-track and a MPP flash as the barrel, while the rotj will have a straight black barrel and t-track, just Google rotj or ESB boba fett blaster
As far as i know, the "carbine blaster" is just another term for the EE-3. As i see it, the ESB version and the ROTJ version are both technically Carbine blasters, one is just a newer/different model