No one can answer that, because height is not the ONLY factor that's going to make a difference in how you look - for example, body composition, genetics, etc., and these two factors will make a world of difference! (As a sidenote, you shouldn't be comparing yourself to your coworker anyways - focus on YOU and forget anyone else).
~Rosie~
I like this answer best! Best rule to remember in and out of the gym is to never compare yourself to another person. Sure, see someone and develop a goal, but don't compare yourself - it's apples to oranges.
Take me, for example... I'm 6'4", about 300lbs. Without saying my BMI or BF%, one might assume that I'm one HUGE dude. While I admit that I am, I'll also admit that I'm not near a stage-walker, probably not even in the off-season! Looking at those 2 measurements alone is NOT a good indicator for comparison, nor an aspiration for goals. Set the goals for yourself based on YOUR dimensions, your definition of "better", and your own metric for success. We can all help you to obtain those goals with loads of great advice (or bad advice, I suppose), but only you can set the goals and put the work in to obtain them.
Take a look in the mirror sometime, a good hard look, and start to pick yourself apart. Don't obsess over everything, but look at one or two parts and work to improve them. Once that is done, maintain them and move on to something else. That's usually how I work it, and sometimes it can be a very slow process to change. I used to have NO shoulders at all, but a year and a half later and probably 10s of thousands of pounds and reps put into it, I finally have shoulders! Next I'll work on something else, then something else, and then something else until I am where I want to be at that stage. Along the way, I'll enjoy the work and celebrate myself for my own sake.
