[Carmel Miller]

I second Barbara’s thoughts on this. Instead of searching for plug-ins you can directly go for building a responsive website design as then you would be able to design a site that can automatically adapt to the screen size changes. Though building a responsive site is more complex and time-taking, however it is a good way to make your site mobile-friendly. You can take a look at this site to understand responsive design better.

[Carmel Miller]

I also agree with the opinion that both the fields has a lot of potential and it ultimately depends on what you are more passionate about. I would however suggest you to take up website designing as I see more growth in that field. There has been an avalanche of changes that have taken place in this industry and the scope of growth is more. Also, with the growing popularity of mobile-optimized websites the demand for web designers is also growing.