nah, it dont look anything like the M3 halftrack. i think its the Russian troop carrier based on Unimog. BTR 20-40 or something. that vehicle did not have an armored top, but the wheels and engine-hood look very similar.
i think the deciding factor if its an APC or and IFV is combat flexability. an APC cannot do much more than transport troops. an IFV has the option of sticking around for the fight. now you can have ATGMs fitted on an APC like the French did with their AMX13R (i hope i got the designation of the 6x6 APC right). so taking on other AFVs is not an essential consideration, but an APC will usually lose mobility or protection as it engages non-troop targets. IFVs can engage targets better bacause the weapons systems are all integrated into the FCS. the FCS is thus a factor in system identification. so combat effeciancy is the where we should look. the better the combat system the more IFV it becomes.