The problem is that there are so many variables when it comes to ayahuasca. First there are many different admixtures. I think that chacruna, chaliponga, jurema and acacia are the most often used admixtures these days (in the industrialised world). Then there's the difference between caapi (various species), rue, or pure alkaloïds. And then the specific mixture of these ingredients: what substance is dominant in a specific brew? The DMT or the harmala's? etc.
Generally, the more harmala alkaloïds are added, the less the experience will have in common with a shroom-experience.
With lower amounts of caapi, ayahuasca and psilohuasca are, visually at least, pretty close to shrooms in my experience. And the nausea or body load is not so bad.
I like ayahuasca and psilohuasca more, when the caapi is not too dominant though. The main difference for me, is mentally.
I find shrooms pretty superficial when it comes to the emotional effects. For me, shrooms are realy lacking in emotional effects.
Ayahuasca is almost the exact opposite of that. I find that the ayahuasca experience is, contrary to shrooms, so full of feeling. Wich is something i realy love about it.
LSD, mescaline and ayahuasca are my favorite psychedelics, exactly because of this element. These substances never leave me cold or indifferent emtionally. While with shrooms i sometimes realy do feel detached from my emotions.