NXT > ardor > ignis all getting tangled in blockchain.
Well, it's ... complicated. By design. It is, in fact, one and the same the whole thing. It is "splitted" with the only purpose of generating more money -and very successfully so far-. NXT will become (slowly) obsolete -and in fact not developed after a while-, once ARDOR is implemented. ARDOR will be the new name of NXT. IGNIS is the first by-product of the new NXT (ARDOR), designed, again, with the sole purpose of being sold to corporations for profit. As the first of such by-products (called technically "child chains"), the developers will give 50% of ownership of IGNIS to those who still own NXT -they need to keep the number as high as possible in order to secure the network- at the specific time of the snapshot. After that the existence of NXT will start slowly fading away completely. The whole shebang is that subsequent "child chains" will be the sole property of the developers of NXT -or, more properly, of the centralized, private, company they have created to such purpose-. The ONLY "benefit" ARDOR holders (NXT ones will have none) will have is whatever is derived from the potential fact that the buyers of such childchains, including IGNIS, will have to pay for them in ARDOR, supposedly by doing that creating more demand for ARDOR.
That, of course, is if you believe what the developers tell you. They are not bound by anything but their words, so they could freely sell the child chains for BTC or any other instrument of exchange.