The difference between an A record vs CNAME is an extra DNS lookup. In case of the CNAME the after figuring out that www is a CNAME to example.com, another look will be done for example.com.
If you are planning on using a CDN or a 3 party acceleration service (Cloudflare), then a CNAME becomes important. Example a lookup of
www.google.com results in the following. See the difference in TTL of
www.l.google.com and
www.google.com:
www.google.com. 36545 IN CNAME www.l.google.com.
www.l.google.com. 294 IN A 209.85.153.104
This gives the flexibility of changing the A record, keeping a lower TTL, doing fancy stuff like geo-redirection, if using 3rd party services.
In this case, it doesn't matter since both are pointing both to the same IP (domain=www) -- as is commonly the case with smaller sites.