Difference between bloginfo('home') and home_url() and site_url()

Question

I have been reading through Codex and other SO and SE posts regarding this. But I am confused.

I used home_url() and site_url() to linking the site's home and it gave same results.

As I was using qTranslate for bilingual implementation. And had its language switcher.

Found later, when clicked on the home logo (used home_url() and site_url()) the current language didn't persist. Because, I am using one language as default and which would just produce http://example.com And for other language it would be http://example.com/ar

Later I found that, using bloginfo('home') solves it. The url now carries the language suffix with the home URL.

As these posts say the bloginfo() functions are being deprecated. I am really confused.