Odds is another way of writing a probability, let me be more clear, they represent similiar information, one is just the probability, while odds is the ratio of probabilities. Example, the probability of flipping a fair coin and it landing on heads twice in a row is .5^2 = .25. This means the probability of this (HH) is 25%. Odds is defined as odds = probability / (1- probability), so here the "odds" of flipping HH is odds = .25/(1-.25) = .25 / .75. This simplifies to odds = 1:3. Now to better explain the difference in probability and odds, the way you would read them:
probability = .25 = 1 OUT of 4
odds = .25/.75 = 1 TO 3 (chance for HH)

chance against HH)
Edit* Also notice how you can get the probability from the odds by rewriting the equation probability = odds / (1 + odds) = (1/3) / (1 + 1/3) = .25. That should clear up the relationship between odds & probability.