Though the structure of the toys was very similar to its predecessor, Beast Machines introduced the concept of a faction of beasts fighting a faction of machines. Both sides were highly stylized. In the case of the heroic Maximals, sleek sculpting coupled with bright colors, translucent plastics, and a variety of action features to create an almost futuristic look. The rival Vehicons were largely military vehicles of Cybertronian origin, mostly blocky and ungraceful despite their in-fiction portrayals. A common thread through the line is the “Spark Crystal”, a translucent plastic dome showing the figure's allegiance a-la the rubsigns of Generation 1.
The line featured one spin-off subseries, “Dinobots,” comprised primarily of molds borrowed from Japan's Beast Wars Neo. Another new marketing concept was pioneered in a more organized fashion. A series-wide package overhaul “refreshed” the look of the series in 2000, branding the toys as “Battle of the Spark”. There is no primary change to the toys correlating to this aesthetic update.
Beast Machines ended later in 2000, barely outlasting the straggling final releases of its predecessor series, Beast Wars. Unfortunately, the line presided over a deceleration of interest in the “Beast Era” concept, which would lead to a series of rapid-fire brand overhauls for Transformers, and a shift to short series and constant resets or package updates.
An interesting footnote to this was that Takara completely skipped this series at the time it was released in the US, and later added it as an addendum in 2004. The series, titled Beast Wars Returns, became a smaller-scale Toys 'R' Us exclusive release.