A capsule and a tablet both perform the same job. However, the capsule will deliver the drug in your stomach directly, since the gelatin covering will take about 60 minutes to dissolve in stomach juices. However, a table will start dissolving right from the time you take it. In ER ( Extended release) tablets there would be enteric coating in layers, so after release of certain quantum of drug, the enteric coating will act as a barrier for some time and after dissolution of that coating, will release the drug again. In effervescent tablets, the tablet will dissolve into fine particles on contact with water.