To me its basically a distinction between:
work - the physical activity itself, or the time spent working.
and
job - the actual position, functions, duties that describe the work you do. Generally used in a broader sense than work.
For example:
I work from 8 to 5.
I will be working at the branch office this week.
and for your examples:
Do you enjoy your work? (This is OK, referring to the actual work functions you perform.)
Do you want to go for a drink after work? (work refers to the time you were working that day.)
As for job:
Do you enjoy your job? (This is OK, but more a question about your overall opinion about your position, what you do, how well you work with other, your boss, etc.)
Did you apply for that job yet?
It was a difficult job but someone had to do it.
I did not understand the job requirements.
Generally, when "stand" is used to mean "is in a standing position", it is accompanied by a location:
He stood in the corner, sipping a whiskey.
They stood around the table, arguing.
She stood by the window, looking forlornly down the empty driveway.
Often this meaning will be expressed in the past continuous, using "was standing" instead of "stood" to unambiguously refer to the condition of standing, as opposed to the act of standing:
He was standing in the corner, sipping a whiskey.
When "stand" is used to mean "get to one's feet", it is either unaccompanied, or accompanied by an event:
He stood when she entered the room.
They stood as the speaker finished his speech.
"Now that you're here, I can finally leave," she said as she stood.
In my experience, stand up is rarely used for "be in a standing position" when it refers to a person; you are much more likely to hear it used for an inanimate object (especially one which is normally horizontal), and again it will most likely be accompanied by a location:
The bedframe stood up against the wall.
Most often, stand up is used for the action of getting to one's feet:
He stood up and stretched
As I approached, he stood up and reached to shake my hand.
Everyone stood up when the orchestra finished its song.
In your first two examples, people changed from sitting to standing when the president came in, and people changed from sitting to standing for the opening of the speech (they did not remain standing for the entire speech, but sat down again after only a moment or two).
Your given alternatives, "get to one's feet" and "rise", both unambiguously refer to the action of changing from a non-standing position into a standing position.
Best Answer
As a 'whole' is 100% of something, then yes, they are technically synonymous. After all, if 100% of your purpose is the office, then a) it is the only purpose you have, and b) you need a holiday.