Caffeine pills are more easily employed in a lot of situations.

For example, you can easily bring along a pill to random occasions where you think you might need a quick boost.

Or you can experiment with them: for a little while, I have been trying out on alternate days Anders Sandberg's caffeine-pill-wakeup idea (where when I first groggily wake up, I take a caffeine pill I left on my bedside, and then go back to snoozing; in theory the caffeine will enforce wakefulness, rather than me hitting the alarm clock and going back to bed for another hour). It would be very difficult to do this if I had to get up, prepare a cup of green tea, drink it, and then go back to nap.