V Beam Laser vs Pulsed Dye Laser, differences?

This is difficult to answer without pictures. This isn't the typical result after a VBeam treatment. The VBeam is a pulsed dye laser. With any laser comes potential side effects including swelling, redness, pain, bruising, burns and change in pigmentation. I suggest consulting with a cosmetic dermatologist who has experience with lasers for after care and treatment options. Best, Dr. Emer

Efficacy from pulsed dye lasers is related to destruction of blood vessels with expected bruising and unfortunately, potential for hyperpigmentation, hence the need to use such products. Link is provided for more information.
V Beam is a pulsed dye laser. 
Pulsed dye laser can cause bruising and swelling and I precondition and treat my patients with a bioflavonoid product called Swell-x pt (post treatment) and also an oral supplement for PIH relief called Scler-X and I find them to be effective. 
For hyperpigmentation relief we use a HQ and non HQ based creams in  the U.S. called Melarase.
Best to see a seasoned physician and laser expert for rosacea. 
Hratch L Karamanoukian MD FACS

The VBeam is a type of pulsed dye laser.  The responses are similar with both devices.  The VBeam will have integrated cooling whilst the PDL will often require an additional cooling device.

A pulse dye laser (PDL) is a Vbeam laser. They primarily target "red" areas of the face such as erythema of rosacea, small blood vessels, etc. Depending on the settings and your skin type/color it is possible to have purpura after treatment is completed. Scarring is always a possibility after any laser used on the face especially in the non-Caucasian population. It is always important to seek a board certified dermatologist when obtaining lasers as dermatologists have extensive laser training during residency and are trained to deal with potential complications from laser surgery. 

The Vbeam is a pulsed dye laser. I am sorry to hear of your bad experience but it is really impossible to say. All lasers have serious side effects when not used properly - whether the incorrect laser is used for your skin type, the settings are wrong, the laser is done on freshly tanned skin - there are many factors at play so while I cannot say what happened, I can say that it is critical that you do not have laser performed by anyone who is not a medical professional with extensive experience.