Even though the differences appear superficially striking, they do not involve any novel body plans (i.e., no new proteins, new tissues, or new organs).
One of the few features that are uncontroversial is the body size: The fossils measure usually 1-5 cm in length.
Ikaria wariootia is just another problematic Ediacaran fossil that could be anything from inorganic artifact to protozoan to cnidarian and yes, maybe a bilaterian worm.
I promised last year to follow up on more alleged Ediacaran animals. Now is a good moment to come back to this, with a new study having just been published in the journal Nature Communications.
Small putative trackways in Siberian rocks are giving evolutionists an opportunity to claim bilaterian animals preceded the Cambrian explosion.