I have several phasing and flanging plug-ins, and the same effects on my Korg Triton. While not identical, the two effects...
one of the main reasons I love and use the DSI Prophet 12 so much is its almost limitless depth of sound design possibilities. instead of coming with a whole bunch of digital, ready-made effects it gives you 4 analog delays. add on top of that 4 LFOs and 2 AUX envelopes giving you the option to make pretty much whatever effect you want. you can make your own custom flangers, phasers, choruses with the delays AND there’s tuned feedback (that can be used in Karplus-Strong synthesis). I will almost always want to make my own stuff if I can. I think it’s cool to have your own custom effects that live only on your synth.
http://www.soundonsound.com/sound-advice/q-whats-difference-between-phasing-and-flanging