According to http://www.nyc.gov/html/dcas/html/work/civilservice_1.shtml, a civil service exam is "is in place to help ensure that the hiring process is competitive and fair." (Refer to the site for more information, which is self-explanatory.) In other words, the civil service exam asks you questions about the job.
A BOSS (also known as a Bus Operator Selection Survey) is a mini-psychological exam, which selects Bus Operators based on your answers. They will have several statements in which you agree, disagree, or just neutral.
Below are some examples. The answers that the MTA are looking for, which will help you get hired, are in parenthesis. If you answer anything else, they may not look to hire you.
1) How comfortable are you speaking one-on-one to a stranger? (Comfortable)
2) Laws which prohibit radar detectors are unfair. (Disagree) [since you want to tell the MTA that you never speed]
3) In your opinion, how often is it acceptable to be a minute or two late for work? (Never)
4) How would you rate your ability to get along with others? (Very high)
5) I am often in a hurry. (Disagree) [keep in mind that the bus is on a timetable]
6) In the past year, how often have you been absent from work? (Less than 5 days) [Need to be reasonable]
7) How comfortable are you speaking one-on-one with your supervisor? (Comfortable) [since you do not make any mistakes]
8) The charge of a ticket is too high. (Disagree) [want to tell the MTA that you are a good driver & do NOT speed)
9) I get upset when people do not turn on red when it is legal to do so. (Neutral) [Again, the bus has a timetable]
10) The kind of supervision I like best is: (Fairly close supervision) [Again, you do not make any mistakes]
11) In a one year period, how many absences from work would you consider acceptable? (Less than 5 days) [Repeat of #6]
Get it? Feel free to PM me if necessary...