Difference between pool sanitizer and chlorinating tablets?

I am a bit confused. We just bought a pool and have it filled. Its a 16 ft X 48 inch pool. What is the difference between Pool Sanitizer (costs 9.99 for four gallon jugs) and Chlorinating Tablets 3" (costs 21.97 for a 4.8lbs bucket)? First what is the difference between the sanitizer and the tablets? Which is better?