According to Kubota site the 3200 has a 91.5 CI 3 cylinder engine, the 3800 has a 111.4 CI 3 cylinder engine and the 4600 has a 134.1 CI 4 cylinder engine.
In short each machine has a different engine size, the 3200, 3800 are 3 cylinder and the 4600 is a 4 cylinder.
In short each machine has a different engine size, the 3200, 3800 are 3 cylinder and the 4600 is a 4 cylinder.