SSN: A Social Security Number or SSN is the most common identifier for personal identification and tax purposes. To be precise, it is used to track individuals for social security reasons and also can be used as a national identification number for tax purposes. SSN is also used for opening a bank account, for applying personal credit, insurance, medical coverage and so on.
EIN: In the aftermath of the formation of a Delaware company, the next step should be getting an EIN (Employer Identification Number) or Federal Tax ID Number since you aim to generate sales and receive payments by starting a business in the US. Although it is named as an identifier for employers, you might not have to have employees to need an EIN.
If you operate your Delaware company outside of the U.S., but still plans to conduct business in the U.S., you need an EIN number for a number of reasons, including for opening a U.S. bank account, hiring employees, and initiating PayPal or Stripe accounts.
The EIN also gives information about your company whereas the SSN provides information about you. Thus, using an EIN is better than using an SSN for avoiding the risk of personal identity theft.
ITIN: An Individual Taxpayer Identification Number which is abbreviated as ITIN is a nine-digit number issued by the Internal Revenue Service (IRS) assigned to individuals who must have an identifying number, but who are eligible for neither a Social Security Number or an Employer Identification Number. Although ITIN numbers can be used for identification, they are primarily used to track payments to individuals for federal income tax and other tax purposes.