There are number of different infected "types" seen throughout the film and game.
Poor souls in the later stages of the infection, their physical forms have been twisted by the cross-species virus. These strikers are more beast than man with animalistic rage, enhanced eyesight, and increased strength. The infection has also given them the ability to spit a form of acid out of their mouths, hitting their foes at great distances.
These folks are almost fully consumed by the virus and highly dangerous. They have similar features of other infected, but can cough up a lot more acid. At times, they will spew out pools of acid that can stick to surfaces.
While non-hostile, there were civillians infected with the plague scattered across Manhattan, too sick to move and had to resort to lying on the streets and sidewalks of the city. They could only hope for Spider-Man to come to the rescue, as the NYPD and other New York City officials could do nothing.
Seen only briefly in the film, S.W.A.T. members were infected with the Lizard's cross-species semen during his attempt to infect all of New York.