Bungalows once meant rustic cabin style accommodation with one or more rooms on the beach, in the mountains or national parks. And they were usually inexpensive.
But all you need to do is to look at Amanpuri's "Pavilions"
in Phuket to see that the old equation is no longer valid.
These new style of bungalow are sumptuous islands of comfort and elegance
in a luxury resort setting.
So now, bungalow simply means a free-standing accommodation. They may appear as bedroom and bath; or suites with a sitting area, more than one bedroom and bath and possibly a kitchen.
Amenities may vary from nothing except shared toilets ... to private swimming pools and spas and with exclusive chefs and attendants
Guest houses are generally low to medium priced accommodations
that would resemble a cheap "motel". They vary from cheap to
moderate. Some have shared baths