A Russian visa invitation (Letter of Invitation, LOI) is a document that allows you to obtain Russian visa (for example, Russian business visa or Russian tourist visa). It cannot be used in place of Russian visa.
We recommend to carry your copy of Russian visa invitation (letter of invitation, LOI) with you as you travel, as Russian passport control officials reserve a right to request it as you cross the border.
To obtain your actual Russian visa, you have to submit Russian visa invitation (letter of invitation, LOI) along with required paperwork to the Russian Embassy or Russian Consulate of your choice.