Tabular layout
Tabular layout - the page contains <table>

Block layout
Block layout - the page contains <div>

Note!
Bad to use (tabular message) <table>
Need to use (block message) <div>
Block layout is better indexed by search engines

The essence of block layout
In the graphic editor, a layout of the site is created: it is marked where which area of the page (header, bottom, sidebar, main content) will be located and how much space to occupy, pictures and backgrounds are prepared.

Each part of the page is placed in its own block <div>
the first block contains the top of the site
the second block contains a menu
the third block contains content
and so on.

Each block is filled with contents HTML, as well as positioned and formatted using markup CSS.

HTML a page is a set of blocks <div> with content inside. The design is often in a separate file CSS.

Principles of block layout
The content needs to be separated from the design.
HTML — separate file
CSS — separate file

This approach makes the structure clearer. The programmer does not need to open the file CSS.
The designer does not need to open the file HTML.
Everyone writes their own code and does not interfere with each other.