The YJ-17 might be a naval version of the DF-17, the YJ-15 is likely the VLS-borne version of the YJ-12, and the YJ-20 seems to be merely the real designation for what was previously known as the YJ-21.
So the only new system displayed so far seems to be the air-breathing YJ-19.
YJ-17 and DF-17 are in entirely different size classes, and are entirely different missiles therefore Their only similarity would be that they're both hypersonic glide vehicles.
YJ-15 doesn't seem to have a booster stage, so whether it's for VLS launch or not could be up for debate (though if it's slant launched if will also still need a booster stage, so we can't definitely say how it is meant to be used).
In terms of "newness," I would say all four are new in the sense that we have not clearly seen their specific designs before.
We have had a brief glimpse of YJ-20 some years ago but that did not tell us much of its design details and a lot was left for us to deduce.