An Arms Race under the original term usage is a competition between two or more parties. The competition is for real or apparent military supremacy. The features of an Arms Race do not differ a whole lot. The idea of an Arms Race is to see which party can produce the larger number of weapons, greater armies, or superior technology. Today the term Arms Race is associated more with competition that has no absolute goal, but a relative goal of staying ahead of other competitors.
Today any company that is in competition, specifically those that design defense equipment are still in an Arms Race. Since the definition is much wider in today’s terminology it could really mean any time of race to the finish where a company beats the competition with products.