Both of the spiders on this page are Whitebanded Crab Spiders (Misumenoides formosipes). The identifying characteristics are: The white ridge across the spider's face just below its eyes. (Another common name for this species is Ridge-faced Flower Spider.) The forward-pointing, V-shaped marking on the spiders abdomen. The eyes: When viewed from the front and slightly above only six eyes are visible. Four are more or less in a row right above the white ridge. Two are above the four. The spiders other two eyes are at the ends of the top ridge and are actually on the sides of the spider's "head". (BugGuide has a photo showing eye placement more clearly than mine.
Crab spiders are ambush predators. They sit in strategic locations, waiting for prey to arrive. Some species of crab spiders have evolved to blend in with bark and leaf litter. Others are more brightly colored and "hide" in flowers.
Typically a female crab spider lays her eggs in the fall and they hatch the following spring. The spiderlings spend the summer eating and growing. They will eat just about any insect that happens to come within the grasp of their powerful forelegs (including other spiderlings). By late summer and fall, the mature crab spiders become more conspicuous. Most of the crab spiders you see are females. Males are much smaller and marked differently.