It always been like this - somekind of "hate" for the Zastava. Same goes for the Santa Barbara. Funny thig is that when they're branded Remington, Charles Daly (Mark X) or Parker-Hale, they're much better actions.... go figure.
Now, the main difference between the Zastava and the HVA 1640 serie is the action size. First, the HVA have a slightly shorter ejection port - bolt draw than what usually seen with N-A firearms. It was made to fit the '06 size, but that's it.
Then, the HVA 1640 are Small Ring actions, while the Zastava is a Large Ring one.
The HVA is a compound design of mixed M/94 and M/98, while the Zastava is a spinn-off of the FN Supreme.
Both have similar floor plate / trigger guard assembly, the early HVA have a milled all steel one while the late Zastava seems to be made of investment casting (steel alloy?).
The Zastava triggers are fully adjustable while most HVA have a single stage Mauser type one, but some have the vintage Tradewinds / Timney adjustable trigger already installed.
Wood quality and finish usually is better on a HVA than a Zastava, but they also had utility grade with cheaper wood.
All in all, it's either you get a rugged reliable and very well made but used HVA or you have a brand new utilitarian Zastava.
If you want to know morw about the Zastava, make a search for the thread I started called post-Remington.