There is a difference between the effect of caffeine in tea and effect of caffeine found in coffee. First, tea takes longer to affect you. It provides more of a subtle lift, and not the fast boost that caffeine in coffee provides. You could say that tea makes you alert, while coffee makes you nervous.

The caffeine in tea increases concentration, alertness, and accuracy, and enhances your senses of smell and taste. It also stimulates your digestive juices and metabolism, including your kidneys and liver, so your body can eliminate toxins and other unwanted substances with ease.

Caffeine acts primarily in our brains and muscles. In tea, the caffeine effect is complemented by another compound found only in tea, theophyline. Theophyline stimulates your respiratory system, heart and kidneys, which is why tea is helpful in maintaining a healthy cardiovascular system.