Green tea has less caffeine than black tea, ~25mg caffeine per 8 ounce cup. However, length of brewing time affects caffeine content, the longer the brew the higher the caffeine. Lipton has listed a figure of 45mg caffeine for their 100% green tea claiming its from 1 to 2.5 minutes of brewing. Try it!
If you are having coffee or tea, avoid creamer and sugar, use splenda and skimmed/almond milk instead. However, Green tea is the healthier option. Perhaps the most healthy hot beverage out there. It is filled with antioxidants and nutrients that have powerful effects on the body such as improved brain function, weight loss as it boosts metabolism and burns fat, a lower risk of cancer and many other great benefits.