Caffeine comes from coffee beans, but it can also be synthesized in a laboratory.
Caffeine has the same structure whether it’s in Coffee, Energy Drinks, Tea or pills/powder.
Caffeine dosages should be tailored to individuals. If you are new to caffeine supplements then the usual recommended start is with a 100mg dose (see warning below). Typically, 200mg of caffeine is used for fat-burning supplementation (impact is still being discussed in scientific community), while acute strength increases occur at higher doses, 500mg and above (again, still under discussion). Researchers tend to use a dosage range of 4-6mg/kg bodyweight.
The structure is the same but its easier to take more than you are used to if you measure wrong. I would personally suggest you avoid powder and go for pill form if you are set on reducing intake through less coffee.
You can read more about caffeine over at Examine.com
Caffeine is highly stimulatory and a systemic vasoconstrictor. Caution should be exerted if one is either not used to caffeine ingestion or currently has high blood pressure.
Caffeine should not be used as a supplement in those with cardiac impairments without prior consultation of one's doctor.
Caffeine can also have an effect on ones quality of sleep; while you may be able to fall asleep, it will be of inferior quality.
Note: Habitual caffeine use leads to tolerance. This means the effects of caffeine will be diminished, often to the point where the only benefit a user experiences is caffeine’s anti-sleep effect. This is an ‘insurmountable’ tolerance, which means more caffeine will not overcome it. A month-long break from caffeine will reduce tolerance.