Piece assemblies are a grouping of pieces which logically take up the same space. Although the solver still considers them separate pieces which may be placed anywhere, you can view them together on the same grid when editing. The editor will also make sure the pieces don't overlap with each other. That is, when a voxel is added to one piece, it is removed from other pieces.
Assemblies are shown in the editor as a group of pieces, a more general concept that will include other types of groups. Piece groups are shown top-level in the list of pieces, with pieces in the group indented below it.
Piece assemblies are a grouping of pieces which logically take up the same space. Although the solver still considers them separate pieces which may be placed anywhere, you can view them together on the same grid when editing. The editor will also make sure the pieces don't overlap with each other. That is, when a voxel is added to one piece, it is removed from other pieces.
Assemblies are shown in the editor as a group of pieces, a more general concept that will include other types of groups. Piece groups are shown top-level in the list of pieces, with pieces in the group indented below it.