The number of lines of codes, in this case, speaks to the amount of features in the framework. Rails is harder to fully understand than Sinatra because there are many, many more features, and it's possible for a beginner to get lost in, or confused by, all those features.

Well, it's harder to understand all of rails, because it has more features. That's a fair claim I think.

However, the question is: Is it harder to understand the subset of rails that does what sinatra does, than it is to understand sinatra as a result?