The "foundation type" in bold reflects what is provided in the plans for this house. If the plans include drawings for a basement (finished or not), your builder will have no trouble building the house over a crawlspace or a slab. The same is true when the drawings include a design for a crawlspace – changing to a basement or slab will present no problems for your builder.
However, if the plans specify a slab foundation, more work is entailed to change to a basement or crawlspace. The answer to the question: "Can I add a basement or crawlspace if the plans call for a slab?" is almost always “yes”, but the new foundation plans must be drawn by a qualified professional, and must (in our opinion) be reviewed by a local structural engineer who’s familiar with the soils, climate, and natural disasters in your area, as well as the local codes and regulations. You’ll need to factor the cost of design and review into your budget.
We strongly believe – as do all of the architects we work with – that all foundation drawings (for our homes or any one else’s) should be reviewed by a local engineer prior to the start of construction, whether your local officials require it or not. The review process is not terribly expensive unless a lot of changes need to be made to the plans, and if a lot of changes are necessary, you certainly want to correct them before building your new home.
By the way, if the foundation says "Basement," but there are no basement drawings in the floor plans displayed, it means that the basement is unfinished.