Seems you misunderstood me.
Rosomak-S is a plain AT team carrier. You have two teams, with two tripods&targeting subsystems, and a ammo supply of 8 missiles in total.
You need to disembark teams, they need to get into position, mount a system, and viola, they can shoot.
It is a battle taxi, not a tank destroyer per see.
So we can't compare it directly to the dedicated, light weight tank destroyer that Tigr with Kornet batteries obviously is.
This is why the difference is so visible.
One would expect much better than 8 missiles load, having a 20+ ton carrier, right?
Edit : just checked my old memory and it is not as good as it used to be
A plain version is more like 16t not 20+, but still ... Tigr is a quarter of that, if not less ...
Well, ballistic protection would be an issue, but it is hardly here.
While Rosomak is a well battle proven platform, used in waste numbers (700+ pieces in the PSZ only) and heavily modified due to Afghan experience, the spikebus is nothing fancy.
It has just the same parameters as "base version", that is 7,62x54 resistance for sides, and 14,5x114 for some frontal arc.
Base Tigr represents the Russian version of armor protection, that is different animal, but in general it's armor standard is slightly higher that STANAG 2, that makes overall resistance to 7,62x39 BZ round from 5-10m. And that is only if we consider it represents the same vanilla standard, because some Tigrs are armored to the level of partial resistance to 12,7x108 and overall for 7,62x54. No idea what is the standard for Kornet carriers, but sure about the protection of Rosomak, belive me on that
So sure, the first is quite better, but can't be considered as "protected".