Bio-Suits are advance suits worn to keep the wearers alive in unsuitable environments. They can also function as space suits.
A bio-suit is more than an environmental suit, it is meant to be worn for prolonged periods of time, years, even lifetimes. They are made to maintain an atmosphere and process any...biological waste the wearer may generate.
Like any tech, it varies per designer and species etc, but Bio-Suits are also more form fitting that primitive space suits, some even sport armor plating.