Dhyan is "prayer" -- dhyan yoga is acheiving things through prayer and meditation.

where as Hatha Yoga is -- is Sun & Moon yoga.....

William Zorn has written:

'True yoga' -- subject(s): Hatha yoga

'The easy yoga exercise book' -- subject(s): Hatha yoga, Yoga

Iyengar, in order to enable more people to practise basic Hatha Yoga, invented "Iyengar Yoga" that is mostly practised outside India. Classical Hatha Yoga is more complex and encompasses a lot more.

Michele Picozzi has written:

'Controlling Herpes Naturally'

'Pocket guide to hatha yoga' -- subject(s): Hatha yoga

'Yoga'

Other variations of hatha yoga in America now include Iyengar, Ashtanga, Kripalu, Integral, Viniyoga, Hidden Language, and Bikram yoga