It depends very much on what's in your brew, but (regardless of whether you can officially call it ayahuasca) any mixture of MAOI's with psychotria viridis, mimosa hostilis, or acacia confusa, is indeed very simmilar in effects to shrooms. Chaliponga is realy different for some yet unknown reason.
For all those brews that are simmilar: they realy are VERY simmilar, but, and i can only speak from my own very subjective experience here, obviously, there is one difference. The mushroom does not realy seem to affect me emotionally, while ayahuasca does.
And i think that has everything to do with the presence of MAOI's.
It would probably be very hard for most people, to distinguish the effects of a chacruna, mimosa or acacia brew, from the effects of psilohuasca.
The effects of a psychedelic are always a bit different anyway. It is the kind of effects that enables you to make a distinction.
The MAOI's in caapi or rue, elevate levels of serotonin, dopamine and noradrenaline in the brain. Mushrooms, as far as i know, do not have any effect on dopamine or noradrenaline receptors.
I think elevated levels of these two neurotransmitters in the brain, have a noticeable effect...it makes everything more euphoric or scary, or pleasurable, or exciting, or romantic, or touching, or ugly, or beautiful. In other words, more meaningfull on an emotional level.
On ayahuasca i have often cried. That never happened to me on shrooms.