Difference between greedy and work conserving scheduler for DAG
If I understand well, it is the same scheduling method with different names. I think Work-conserving Scheduler is the more "official" one. "greedy" can indeed qualify many aspects of the problem and one should always precise which. greedy algorithm is a paradigm not a specific method for a specific problem.

Anyway about the upper-bound, the presentation of your last link says that it is:

$T &lt; (T_1-T_\infty) / m + T_\infty$

but that a simpler one is generally used:

$T &lt; T_1 / m + T_\infty$

Of course the latter is greater than the former but both are true. Also note that they are both equivalent to $T_\infty$ when $m$ tends to $+\infty$.