Both the words are very important traits of a personality carrying difference in meanings but at some point or the other they are found augmenting each other or defaming each other at the same stance. Aptitude is your indigenous or inherent ability towards some specific aspect/discipline of life and attitude is the way of looking at it. To much an extent, aptitude is inbuilt and can be polished further, whereas, attitude mostly is stimuli borne and the stimulus can be upbringing, social environments, personality complexions, behavioral deficits, educational aspects etc.
Aptitude includes your skill set, knowledge, experience, education etc. whereas attitude shows your personality traits including your upbringing. Aptitude always has a reasonable weight but the attitude weighs greater always. It is the attitude which helps you attain the unlimited heights or to fall into the worst depths.
Organizations, now a days, look more for the positive attitude then the aptitude, knowingly that the later can be inculcated but the former is hard to mend.
I do not say that attitude alone serves everything but it does to the most of the part and rest is accomplished by the inbuilt acumen, the aptitude. The aptitude to learn or to grow or to be what one wants to be. So, safe to say that you need to have strength in both the traits to excel but still, positivity in attitude pays you the most.
Open to discussion as always and would love to have your comments in support or against.