A lot more expensive than fleece. Better is debatable! "Vetbed" is short for veterinary bedding - what the vets use when treating animals particularly after surgeries. It's sold mostly for dogs, but it's good for guineas too.
The basic pros and cons of Vetbed are:
Pros:
Very soft, fluffy, cosy surface;
Wicks urine down to base, so surface remains dry;
Can be washed at high temperatures (90 degrees if you buy the Petlife International Original Vetbed
)
Excellent bedding for post-op recovery;
Lasts years.
Cons:
Expensive;
Hay and poops can wedge themselves down between the soft "bobbly" fibres - not as easy to completely brush off before washing as fleece is;
Bulky, heavy to wash so you can't put much into the machine at a time.
Both fleece and Vetbed work well for most piggies, but what works for one pig and owner may not work for another.
You can buy Vetbed online, or in some pet shops. Petlife is the original Vetbed, there are many imitations (such as Profleece) but as long as the Vetbed has a firm back/base then the only difference is that the imitations cannot be washed at 90 degrees.
Mine are on fleece and do brilliantly on it, but they do love their Vetbed as well - I tend to have a few pieces of Vetbed in the cage as an extra cosy area.