Can someone explain the difference between the IR-1 and the CR-1?
Thanks

Brad

Length of marriage

Under 2 years = CR1
Over 2 years = IR1

you receive a CR1 if you were married for less than 2 years at the time of entry into the US. Your green card will be valid for 2 years. You are then a Conditional Permanent Resident and will have to file for Removal of Conditional Status 2 years after entry. (to be exact 90 before the 2 years are over)

you receive an IR1 if you were married for more than 2 years at time of entry into the US. Your green card will be valid for 10 years.

Almost right. The distinction between whether you receive an IR-1 or CR-1 visa is whether your marriage was at least two years old at the time of visa issuance. But the much more important distinction between whether you receive conditional or unconditional lawful permanent resident status is whether your marriage was at least two years old at the time of entry. People who enter on an IR-1 visa always receive unconditional status, because they always enter after their second wedding anniversary. Most people who enter on a CR-1 visa receive conditional permanent resident status, but some enter after their second wedding anniversary and therefore receive unconditional status.

Furthermore, the "90 days before the 2 years are over" is the date when the window opens for filing removal of conditions. The window closes at the two year mark. You can file for removal any time during that 90 day window.

Immediate Relative status will be granted if when one enters the US their marriage is two years or more. If they were granted a CR-1 visa, the officer at POE WILL grant Immediate Relative status. One must however bring it to their attention. There are many members that have been in this situation.

From USCIS
What Is Conditional Residence?

If you have been married for less than two years when your spouse enters the United States on an immigrant visa, the permanent resident status is considered “conditional.”