- Draw an 8.
- Draw 8.
What does each imply, and what are the differences between the two?
The difference is that one would not say #2. . .
unless it was already understood that it was some kind of card game in which one might draw eight cards. How many cards do I draw? Draw eight. Or, perhaps in kindergarten: How many squares did you want me to draw? Draw eight.
Your sentence #1 asks the hearer to draw a "figure-eight"; i.e., the numeral "8".