I do know of 311 & what I know about it is that it is for non-emergency gov’t services; potholes, street / traffic lights out, parking complaints, quality of life issues, etc. whereas 211 looks to be helping people.
(Food Pantries and Soup Kitchens · NYC311) directs people to help as well - but my point is that there is no 211 in NYC . It’s not a universal service and that might be why you never heard of it.
211 is used in the NYC metro area, specifically on Lawn Guyland, according to what I looked up; it is also in my state. I had heard 988 was coming well before it went live, possibly a year or more; this one is live & had never heard of it. I’m glad it exists as it sounds like a good idea; it’s just they need to put some of their budget towards marketing so that people know it exists.
<something>11 is always a public service of some sort or another, but most of them vary from one locality to another. 911 is the only one that’s universal, but there’s also often 411 for directory information (though that’s probably outdated now, when everyone can just Google numbers on their phones), 211 for safety-net services, a number (811 around here) for utilities (so you don’t accidentally cut a power or sewer line or something when you dig), sometimes the non-emergency police number is of that form, etc.