Do you have DAS? If you don't have a heads-up display, you don't have ProActive and therefore you don't have DAS.
Let's assume you have DAS.
Standard mode is standard steering and standard transmission.
Personal mode lets you choose your personal settings for Steering, Trans and turn Active Trace Control on/off.
The difference between Dynamic and Dynamic+ steering is mostly the amount of feedback you get in the wheel. DAS was originally conceived as a way to to tune bad feedback out of the steering system. Its also what enables the car to do its Active Lane Control ('self driving') tricks. The first version of DAS in the 2014 Q50 tuned almost all feedback out of the wheel. In other words, you didn't feel any feedback in the steering wheel if you hit a pothole going around a corner. People, especially journalists, complained that it felt "numb". So in the next version (2016 Q50), Infiniti re-introduced feedback into the wheel. That's when Dynamic+ came into play. QX50 has the next iteration of this system (I often refer to it as DAS v.2.5). It is also sometimes referred to as Sport and Sport+. Dynamic+ is tighter steering and gives you more feedback in the wheel.
For me, I change my personal mode depending on how and where I'm driving. Sport mode gives you tight steering with feedback and elevated "shift" points in the tranny. It works well on twisty, hilly roads. I also like the tighter, more feedback-y steering on back roads, even if I don't care about the elevated shift points. So my personal mode in my Q50 and my wife's QX50 is typically set to Sport, or Dynamic+ steering without the sport tranny.
Does that help? If not, ask for clarification. Or better yet, go play with it a bunch and come back and give us your feedback.