Getting the Answers - Answer Key vs Answer Bank vs Answer Block
Answer Key: The answer key for a math worksheet is simply the worksheet that shows the answers.
The answers are shown in place with the math questions making for an effective review for students; but if budget is a concern, the printed answer keys use as much paper as the printed worksheets.
In the animation below, the worksheet and answer key also display the Answer Bank and an Answer Block as part of the worksheet so you can see how the three features are displayed on a page.

Answer Bank: Answer banks are designed to provide students with a way to self-check their work; it is not intended to be the answer key. The answers for the worksheet are all in the answer bank, but in random order.
In many cases a teacher may want to hide/not show the answer bank because it is unnecessary (i.e. for basic facts practice), but it might be helpful to use when students are taking home worksheets with more difficult work (i.e. long division).
In the animation below, you can see that the answers are in random order in the answer bank; and you can see how to hide the answer bank if you don't need it.

Answer Block: Answer blocks are only the answers in order, and are intended for correcting the questions. Answer block sections can be placed anywhere after an exercise set, so after just one set of questions, or after multiple sets of questions.
Answer blocks have their own text formatting options; and because answer blocks are in their own section, they have section options that includes a Begin On New Page option. What this means is you can have the questions for the students on one page of the worksheet, and the answer block with the answers on separate page.
In the animation below you can see how to add an answer block section after the questions on the page; the formatting options for the text in the answer block; and how to access the section options for the answer block to place the answers on a new page.
