In short, ADLS Gen2 is the combination of the current ADLS (now called Gen1) and Blob storage. Gen2 is built on Blob storage. By GA, ADLS Gen2 will have all the features of both, which means it will have features such as limitless storage capacity, support all Blob tiers (Hot, Cool, and Archive), the new lifecycle management feature, Azure Active Directory integration, hierarchical file system, and read-access geo-redundant storage.
A Gen2 capability is what is called “multi-modal” which means customers can use either Blob object store APIs or the new Gen2 file system APIs. The key here is that both blob and file system semantics are now supported over the same data.
One very interesting thing to me is that Gen2 pricing is half of Gen1.