When I booked my stay, the site I booked through advised me “Payment will be taken Directly by the Hotel” what does this mean?

This means that even though you have booked through a third party, BLOC Hotels are the ones who will be taking the payment directly at the time of booking.

Is there any difference/advantage between booking online or by phone?
Rooms booked online take advantage of being able to choose Advance Purchase rates generally saving between £5-£10 per room, also Best Available/Flexible Rates which give you the flexibility of amending (+ any rate difference) and free cancellation up until 1400 on the day of arrival.