Photos has a very different library structure. There are no more projects - just the library, and you can define albums.
Projects have been replaced by Moments, and the moments are created automatically, based on the dates of your photos and the location. A Moment is a set of photos taken at the same time at the same place. Related moment will be visible as a collection.
When you migrate your Aperture library, Photos will create moments, so make sure all photos have location data. You cannot add locations in Photos, but they are important to have meaningful moments with some descriptive title. So assign locations in Aperture, while you still have Aperture.
All your projects will be replaced by albums with the same name as the project. You will find them in a folder called iPhoto Events.
See this Help text: How Photos handles content and metadata from iPhoto and Aperture - Apple Support
Photos will not suffice for your needs, if you used Aperture's power - see my comparison here:
Photos - Is it worth the hassle?
Photos has some nice features, by I do not see, how to manage a large photo library with it in an efficient way.