If you're interested in learning some illustration and publishing "lingo" here's a list for you to enjoy. It's not imperative that you know these terms, but sometimes it can be helpful.
An illustration that resides on one side of one page of a children's book./
Also called a "two-page spread" because the one illustration "spreads" across two facing pages of an open book. For example, if your book size is 8" wide by 10" high, then a two-page illustration size for your book would be 16" wide by 10" high.
A low-resolution image that is relatively small in file size and travels easily by way of email. By comparison, finished full-color children's book artwork is enormous in file size and totally unsuitable to email. Finished children's book artwork is normally delivered through ftp server upload (not available to most authors) or regular mail on CD.
A lower quality (but very adequate) image intended for viewing on a computer screen. Not suitable for printed materials such as books.
Artwork that is ready to go to the printer. It has been created or scanned at a very high resolution (300 dpi) and will look great in your printed book.
An illustration that is printed to the very edge of the book's page.
Artwork that is created by combining the finished book illustrations with the text from your manuscript into its own unique file. This artwork is mandatory for the publication your book.