"To do" generally talks about jobs, tasks, duties that one accomplishes. (fazer) It is often non-specific. "I have to do the work. She does all of the calculations." "To make" usually indicates a finished product or result of the action (fabricar). It is usually specific. "I have to make a table for my class. She makes a delicious desert." "To do" in all its forms also helps English form questions or negatives: "Do you want to go?" "I didn't need the money."