Lots of differences between the V and VA series. The V series was a parts built tractor with a Continental 124 flat head engine and a Clark transmission and rear axle. The V and VI and VO tractors were short coupled standard tractors and 24 inch rear tires and fixed wide front axle. VC tractors were built with the same continental engine, stilled used Clark transmission and rear axle, but different transmission gears. Rear tires could be 28", 30" or 32 inch. VC was a row crop cultivating tractor and could be had with single front, narrow tricycle or fixed or adjustable wide front.
VA series tractors were all Case built tractors and used 124 Cu. In. overhead valve engines. VA, VAI and VAO tractors were fixed wide front on 24 inch rear tires. VAC tractors were row crop cultivator type tractor could have 28", 30" or 32" tires and could have single front, narrow tricycle or fixed or adjustable front axle.
About the only parts that will interchange between V and VA series tractors are the rear wheels.
Other variations of the VA series could be VAH or VAS basically a VAC with dropped rear axle housings and taller wide front axle.
There are other variations, but won't go into that this morning.