1) Load option allows loading of large email lists in seconds. Load works only with the .txt and .csv files. The duplicated email addresses within the list are skipped.
The format of the .txt or .csv file, from which you load the emails, must be as follows:
The first line must contain the "Email" word. You can manually add this line at the beginning of your email list if it is not there. To load a list of emails, put the cursor on the list name under My Lists section and click Load button on the Toolbar. Select the file to load and click Open. You will see a progressive bar showing the loading process. If you cannot see your emails in the AEV after loading is complete, just click Refresh button on the Toolbar.
2) Import Wizard allows importing the emails from different file formats. Plus, if you have additional fields in your file such as First name, Last Name, Company Name, etc., Import Wizard allows you import these fields too. But you have to create necessary columns for these fields beforehand when you create a new list. Import Wizard works slower than the Load option because you need to go through all the steps and manually map the fields from your file to the respective fields in the AEV.