How to configure multiple subdomains in 1 Hosted Zone?

I have a registered domain xxx.com.

I would like to make an aaa.xxx.com and bbb.xxx.com subdomains, and point them to different locations (in my case, CloudFront distributions). I found conflicting documentation even on the AWS Docs about this use case, and there's a lot of confusion out there on the net in different tutorials.

For the time being, I have the following configuration in Route 53 for the public hosted zone xxx.com:

xxx.com             NS              ...
xxx.com             SOA           ...
<rnd>.xxx.com  CNAME     ... (needed for the ssl cert)
aaa.xxx.com       A               Routes to CloudFront1
bbb.xxx.com      A                Routes to CloudFront2

If I copy&paste the CloudFront2 location here to the browser, I get to the proper static website I'd like to use. If I go to the address bbb.xxx.com, then I see the contents of aaa.xxx.com*. I have waited 72h+ to wait for the DNS caches to clean up, but still no change unfortunately. I'm suspecting I might be doing something completely flawed here :-)

So, my question is: how should such a normal config would look like where there is a root domain + 2 subdomains pointing to different location? Any articles, links would be more than welcome!