There are are several web tools that can help you in both web layout as well as web design, however here is a brief description of both:
Your design is the overall look of your site. A layout is the structure of the main content areas of a single page. Your site can have only one design, but you can choose a different layout for every page.
Your site design includes a color scheme, a basic page setup, a default set of type styles (fonts), and often a background image or images. Your site design also helps determine where on each page your site title, page title, site menu (navigation bar), and footer appear.
A page layout, on the other hand, controls the body of your page by determining where the main content of your page will appear. Each page has three main content areas; each layout arranges those areas in a certain pattern. A layout also specifies whether a page will include a page title. When you set up your site, we'll choose the layout we like best for each page, but you can change your layout anytime.