So recently I posted on twitter about a sudden gain in strength:
I have conquered pull-ups! On Saturday night I could do 1.5. Today I could do 11! (Chinups were always easy.) #fitness— Steve Kemp (@Stolen_Souls) June 15, 2015
To put that more into context I should give a few more details. In the past I've been using an assisted pull-up machine, which offers a counterweight to make such things easier.
When I started the exercise I assumed I couldn't do it for real, so I used the machine and set it on 150lb. Over a few weeks I got as far as being able to use it with only 80lb. (Which means I was lifting my entire body-weight minus 80lb. With the assisted-pullup machine smaller numbers are best!)
One evening I was walking to the cinema with my wife and told her I thought I'd be getting close to doing one real pull-up soon, which sounds a little silly, but I guess is pretty common for random men who are 40 as I almost am. As it happens there were some climbing equipment nearby so I said "Here see how close I am", and I proceeded to do 1.5 pullups. (The second one was bad, and didn't count, as I got 90% of the way "up".)
Having had that success I knew I could do "almost two", and I set a goal for the next gym visit: 3 x 3-pullups. I did that. Then I did two more for fun on the way out (couldn't quite manage a complete set.)
So that's the story of how I went from doing 1.5 pullus to doing 11 in less than a week. These days I can easily do 3x3, but struggle with more. It'll come, slowly.
So pull-up vs. chin-up? This just relates to which way you place your hands: palm facing you (chin-up) and palm way from you (pull-up).
Some technical details here but chinups are easier, and more bicep-centric.
Anyway too much writing. My next challenge is the one-armed pushup. However long it takes, and I think it will take a while, that's what I'm working toward.