Invitation from Russian Organisation: 
original may be required by the Consulate. Please request information from the consulate issuing your visa.

Electronic Invitation:

is an electronic invitation with a barcode sent to the customer, a printed-out copy is needed to is required to obtain a visa, and does not require sending by post

Telex (electronic code of invitation):

is a kind of personal code that is sent directly to the consulate or the embassy where you are going to apply for a Russian visa, it does not require sending by post.

For your information:

In accordance with current GDPR regulations, your data is stored on a secure server for the time it takes to provide the service. We do not keep any information or documents once the service has been provided, except your name, email address and the type of service requested (no advertising or sharing with third parties).