If you talk about the magnitude of something, you are talking about its great size, scale, or importance.
An operation of this magnitude is going to be difficult...
These are issues of great magnitude...
Magnitude is used in stating the size or extent of something such as a star, earthquake, or explosion.
...the 1.2 magnitude star Fomalhaut...
The San Francisco earthquake of 1906 had a magnitude of 8.3.
You can use order of magnitude when you are giving an approximate idea of the amount or importance of something.
America and Russia do not face a problem of the same order of magnitude as Japan.
In mathematics, if one amount is an order of magnitude larger than another, it is ten times larger than the other. If it is two orders of magnitude larger, it is a hundred times larger.
The time delay would be smaller by eight orders of magnitude.