Not to me:
bachelor flat = a smart flat full of gadgets, etc. We often say 'bachelor pad' in BrE, though the word 'pad' is not used much nowadays for 'home', but survives in this collocation
studio flat/apartment - a flat where the sleeping and living areas are in the same room, though with a separate bathroom. the kitchen could be separate or part of the general living area.
bedsit- a sleeping/living area, but the bathroom is probably shared- a room in a house would be a bedsit