I've always thought that the Vasudans had a larger fleet then the GTA, relying more on cheaper and fast-to-produce designs like the PVF Anubis and the PVC Aten to do most of the fighting, while the more advanced designs (such as the Seth and Horus) would be granted to use on elite-units, operating out of destroyers such as the PVD Hope.
As such, the PVN would most likely be formed of large partion of conscripts (kamikazes) rather than more trained and skilled crew, operating on destroyers and such.
GTA League of Defense would on the other hand, be a very highly-trained, professional army, relying more on the skill of the pilots and the general high-quality of their designs rather than numbers, meaning that their fleet would be smaller in size compared to the PVN.
And as for the Battle of Vega (
) in 2333, the 4th fleet was mostly likely ambushed by, say those elite Vasudan units, using bombers, advanced fighters designs and of course, the Typhon. Plus, the Vasudans had the element of surprise in this battle, since the GTA underestimated the power of the PVD Typhon.