For buying a laptop, which one is better ? 14.1 or 15.4?

Answer:

Unless the extra freight is an annoyance when you are toting it around, I would always (all things individual equal) opt for the larger screen. It is smaller amount strain on the eyes and more room for info.
I wouldn't consider that to be the most important sector of the laptop. That's just the peak, not really too big of deal and not too much of a difference. I would travel with which ever one have the most memory or better processor, those are the more important things.
Depends how portable you want it to be, really, it adjectives boils down to personal preference.

Are you going to dangle out with it adjectives day long to work and arts school?

Or is it going to sit on your desk for the majority of the time?

The best thing is to try one and see what you're comfortable beside. I have a 15 MacBook Pro and love it; I don't presume I could use any less blind size.
small one.
15.4
I would consider getting a 15.4 rather than a 14.1 because it's bigger.