Bumblebee was consistently described and depicted as one of the smallest of the original 1984 Autobots. This, of course, ignored the fact that other Minibots were essentially the same size (especially Cliffjumper, whose mold was so frequently confused with Bumblebee's back then that, as often as not, new Cliffjumper toys are often just straight repaints of Bumblebee toys), and as later explicitly-small Transformers like the Micromasters were introduced, it became a less important aspect of Bumblebee's character as time passed. When the "Smallest Transforming Transformers" Bumblebee toy came out in 2003, it may be seen as a return to Bumblebee's roots, although in fact the other toys in this line were, again, roughly the same size.
Seen here on the left alongside Smallest Transforming Transformers Bumblebee's larger G1 namesake, one can easily see how paint application technology had advanced in the roughly two decades since Bumblebee's original release. Smallest Bumblebee now sports painted headlights and a tampographed faction symbol. Smallest Bumblebee also sports painted hubcabs, but this comes at the cost of the wheels being freely movable, as with G1 Bumblebee's rubber tires and chromed, free-wheeling inner wheel parts.
More sacrifices are apparent in robot mode, where the smaller size causes Smallest Bumblebee to have a right arm with a "shoulder" located roughly at Bumblebee's stomach! The transformation mechanics of the two toys is roughly similar, but G1 Bumblebee was able to hide the lower hinge on its right arm (vs. the parallel attachment for the left arm) by virtue of a slight adjustment upward before applying the hinge (coupled with a corresponding adjustment downward on the G1 toy's left arm), allowing both shoulders on the G1 toy to look like they're at the same height. Not having these adjustments, Smallest Bumblebee's arms are forever uneven. He also loses the independent legs of the G1 toy, although this just puts Smallest Bumblebee in good company with many other Transformers (such as Seaspray and Powerglide).
The Smallest Transforming Transformers are a bit of a forgotten footnote today, but coming out several years before the "Classics" line hit the shelves, they were eagerly sought-after by G1 fans anxious for new toys of their favorite characters... at any size. Definitely worth paying attention to again today.