As a response to 7, 10 was holding it in so he could see all his companions again as himself and could do no longer when he reached the TARDIS. The build up of energy made it explode out of him whereas with 9 he just let it happen.
In his many adventures, the Doctor has to manage time, space and relative dimensions: luckily though, those of us on Earth just need to manage our time… Shame you can't get this with your choice of doctor - ten is my fave!!!
There is that one person that enters your life and makes everything colored and shiny, like a blind man seeing for the first time... without them your world is just a dull grey... This is why we need that one person in our lives, to bring the color into our lives