Excellent question and highly misunderstood!
You would need to read the Declarations and Bylaws, a copy you can get from the title company, county recorder, or seller. But basically, most condos follow the same rules (but not always):
Common Area is owned equally by everyone and managed by the Association. Normally, this is structural in nature and includes anything that serves multiple units at once. Examples would be roofs, parking lots, support beams and lumber that hold up roofs and walls, greenspace, trees, common landscaping, siding, shared utility lines that span more than one unit, sump pumps if it serves multiple units, etc. Your dues is based on the cost of maintenance and improvement of these items divided over the number of owners plus a bit to save for the future.
Limited Common Area: Many condos carve out a space of the common area and allow you limited ownership of it. An example would be a patio area, or assigned parking space. Many condos allow owners to modify this space to a limit, even while mainatining the space, with the general rule that you maintain your stuff in the area. So if you have a patio with flowers, the flowers would be yours and the patio may be theirs if the builder furnished it. There are wide variations here, so read your decs & bylaws.
Your space: Normally defined as drywall in, from basement floor to the bottom of the roof decking. So if your condo was destroyed, they would probably rebuild to drywall and starting at the paint all would be yours. Attic space? Doors? Windows? Electric box? Sump pump? Furnace? Plumbing? Yep-in most cases its all yours! Even though you need permission to replace your windows and may need a certain brand or style, they are still yours.
Make sure you read all the paperwork as this changes in high-rise vs ranch condos, and each set of condos has different rules, but this gives you the basics.