1.Difference between shared hosting and dedicated hosting-
The primary difference between dedicated and shared hosting is how the web server is used. With Shared web hosting, the web server is shared between many different websites. With dedicated web hosting, the web server is dedicated to your web site. Both services have their advantages and disadvantages.
Dedicated hosting is any day expensive than shared hosting.
2.What is disk space and bandwidth transfer?
The disk space that you contract for from your web hosting company is the disk space that you will use for your web site (and website logs if you have logging enabled). You can determine how much disk space you will need by looking at the amount of space that your website is using on your own machine.
If you got lots of pictures or other image files there will be a need of more disk space.
Bandwidth or data transfer, refers to the amount of data that has been transmitted by your web server to visitors of your website. For example, if you have one page on your web site that is 10kb large, and that page has one image on it that is 90kb large you will transfer 100kb of data for every user that views that website. So, 10 users would mean that you used 1,000KB of bandwidth.
Bandwidth and disk space needs vary tremendously based on the type of web site that you are hosting and the volume of visitors to your web site. Largely text web sites do just fine with several hundred megabytes of diskspace and bandwidth. We suggest that you speak with your web hosting company and have them help you select the right plan for you.