Vado 3.0 is Class 1 while 4.0 is Class 3 with a stronger motor. The 3.0 has a smaller battery, too.
You would probably learn about that if you visited the Specialized subforum or posted there.
P.S. You are in Canada. There, both bikes are 32 km/h but the 4.0 has a stronger motor and larger battery as well as better components.