UE4 is a general purpose engine from ground up.
CryEngine until version 3 was designed with FPS Open world in mind. With the latest iteration, they have redesigend things and have added support for other game types as well. However getting something other than FPS type game in the latest version is still much more difficult than in UE4.
Cry-Engine also does not allow you to define Materials like UE4 does. Their Material editor has some pre-defined templates and you can only change the values of params (like we do with 3DsMax default material properties). If you look closely, you can see a paramter in material property called ‘heat’. At first I thought was used to generate dynamic blakcbody . But it turns out that it is used to render Night Vision effect in Crysis game. So that Material proeprty exists there purely for the Crysis game. We can ofcourse use it but it is proof that the engine was designed soley for that kind of games (atleast in the initial stages).
Its like the iffernce between a General purpose building that lends space out for offices. You can make the rooms into almost any kind of office or establishment. But there buldings designed with restaurents in mind. They might have built-in gas conenction, air filteration… So if you plan on starting a restaurent, taht is agood thing and you will feel more comfortable and efficent. But if you want to start a Book store, then it is better to go with the fisrt option OR look for a building designed with book stores in mind. But trying to convert a restaurent into book store could be diificult. Ithink of UE4 as a general purpose building and CryEngine as the Restaurent building in .
Both are great engines. But each one is aimed at different targets, I think
And coming back to topic, Foliage assets in CryEngine are better becuase they have some built-in hard-coded stuff done for Interaction with foliages, becuase the original Crysis wanted it. And also becuase of the high quality art. UE4 can do pretty decent with Foliages if you have a good asset. And if you really need crazy custom physics stuff, I think you can edit the source code and add it sicne we have source code access now.