About "TIME SHARING"

I've been pretty busy recently with time sharing, what is the difference between "time building" and "time sharing" ?? let me try to explain...
There are 2 ways to build flight hours during commercial phase of the training, 1st way is time building, where you fly solo, or with an instructor, you log PIC time and you pay for the whole flight. As you can already tell, this way is the expensive way. And then there's the "Time Sharing", where 2 pilots fly together and share the expense of the rental. One might ask.. " but you can only log half of the flight time as PIC (pilot in command)", ha, that's the beauty of Time Sharing.. BOTH pilots can legally log PIC, why ?? because during time sharing, 1 pilot should be "under the hood" and fly as "simulated instrument flying, and the other pilot should be the safety pilot, that way both pilots are acting as PIC. thus, we get the hour, and we only pay for half of the aircraft rental.
When I time share, normally the pilot on the left is the flying pilot, and the other pilot handles the navigation and radio communication, during a time share, we switch position so we get to practice both tasks..
sometimes we fly to uncontrolled airports, sometimes we fly to big class C airports, both are a lot of fun! uncontrolled airports we are responsible for communicating with other traffics, talking with other pilots so we don't run into each other. Big airports like San Antonio, we get the thrill by making parallel approaches with airline traffics, everything is pretty serious when we go to big airports... we need to try our best to show them our professionalism, it's a very good practice as it is as close to our future job as it gets, we can have a better idea of how the pros do it..
I have 160hr now, when I reach 240, I will start my multi-engine training. . I'm almost going home!