So if you playR$1/$2 live cash games and buy in for 100bb, orR$200, then you should have a bankroll of at leastR$4,000. And if you playR$25NL on online and buy-in for 100bb then you should have a bankroll of at leastR$500. This rule ensures that you never buy-in at the table for more than 5% of your bankroll.
Online poker is harder compared to live poker. The natural setting of live poker allows you to feel the game more physically with the rules set in your mind differently compared to looking at a screen. Online players are more rapid due to the sheer number of hands they can play per hour compared to live.