They definitely discovered a particle. There aren't any other particles besides the Higgs that have been predicted to exist at the energy levels they've been investigating. They can't claim that the particle they have discovered is definitely the Higgs because the Higgs has certain properties that still need to be verified as pertaining to the newly discovered particle. But a new particle has been discovered. It already shows signs of being the Higgs by exhibiting certain properties (mass is within the range), but because physics isn't economics, physicists are are being extra cautious because they take seriously their credibility and even though they're within 5 sigma of certainty to claiming the particle is Higgs's, they're going to wait until they're ultra sure. It most likely is the Higgs, but because physicists are not social scientists, they don't jump the gun. This is a good thing, not something to look down on.
"I never submitted the whole system of my opinions to the creed of any party of men whatever in religion, in philosophy, in politics, or in anything else where I was capable of thinking for myself." - Thomas Jefferson