geometry STAsText returns spatial text without the Z and M values carried by an instance. I compare it with ToString using two points. Identical XY text can hide a difference in the original payload.

geometry STDistance measures the shortest distance between points belonging to two represented shapes. I compare an interior gap with an endpoint gap. Intersecting shapes provide a useful zero-distance case.

geometry STGeometryType identifies the represented shape type, which carries more information than its dimension. I compare single and multiple shapes in one small query. Equal dimensions do not mean that their structures are interchangeable.

geometry Collections hold member shapes that STGeometryN can return individually. I extract a point and a line from one fixed collection. A third request deliberately exceeds its member count.

geometry STIsEmpty tests whether an existing spatial instance has an empty point set. I keep that condition separate from SQL NULL. A missing database value and a present empty geometry are different inputs.