Caffeine is one of the most used substance all over the world. Ideally it should be consumed as less as possible. Find out Flat White Coffee vs Liqueur Coffee caffeine content in the following sections. However Flat White Coffee Caffeine levels and Liqueur Coffee Caffeine levels may differ with their brands, quantity of additives used, types of additives used etc. Below we have given you a generalized idea of safe levels of caffeine in Flat White Coffee vs Liqueur Coffee, their side effects and benefits.