My feeling is that a tile is simply a sub-type of plate; i.e., one without any studs.
By the "natural order of things," a plate is a flat part with studs on it. Sometimes you find that the plate has had a corner cut off, say, or some of the studs removed, so now you have a modified plate (or as BL calls it, a "plate, modified")—but you still have a plate.
By extension, if you keep removing studs until you haven't any left, you have a studless plate called a "tile". But if you stop before that point—you remove some of the studs but still have some left—you haven't reached "tile" yet, you're still just in the "modified plate" world.
On the other hand, I understand why a part that's mostly smooth does look like, or function as, a tile to a certain extent. But where's the limit? If we take a studless 4x6 tile and start adding studs, eventually we might end up with a 4x6 tile that has 24 studs on it—also known as simply a "plate".
If we wanted to recognize "tile" as an optional keyword for tile-like parts that have some studs, perhaps the rule could be that only studless plates are categorized as "tiles", but any plate that is missing studs on at least 50% of its contiguous surface area is entitled to the optional "tile" keyword. So the 4x6 plate with studs around the edges would qualify (12 of 24 nominal studs are absent), but not the jumper (1 of 2 nominal studs is absent, but not within a contiguous area).
By the "natural order of things," a plate is a flat part with studs on it. Sometimes you find that the plate has had a corner cut off, say, or some of the studs removed, so now you have a modified plate (or as BL calls it, a "plate, modified")—but you still have a plate.
By extension, if you keep removing studs until you haven't any left, you have a studless plate called a "tile". But if you stop before that point—you remove some of the studs but still have some left—you haven't reached "tile" yet, you're still just in the "modified plate" world.
On the other hand, I understand why a part that's mostly smooth does look like, or function as, a tile to a certain extent. But where's the limit? If we take a studless 4x6 tile and start adding studs, eventually we might end up with a 4x6 tile that has 24 studs on it—also known as simply a "plate".
If we wanted to recognize "tile" as an optional keyword for tile-like parts that have some studs, perhaps the rule could be that only studless plates are categorized as "tiles", but any plate that is missing studs on at least 50% of its contiguous surface area is entitled to the optional "tile" keyword. So the 4x6 plate with studs around the edges would qualify (12 of 24 nominal studs are absent), but not the jumper (1 of 2 nominal studs is absent, but not within a contiguous area).