DHenrique - Without seeing into your actual conf lines that configure the logging on your server, we can only guess.
I am guessing that your access_log records web requests that came in on port 80 and ssl_access_log records requests that came in on port 443.
So, a request to http://yoursite
would get logged to access_log, a request to https://yoursite
would get logged to ssl_access_log. That's really the only difference... unless your config files specify different logging formats for one or the other.
Apache matches a web request to a particular vhost and if that vhost has an access log configured, the line will get logged there. If no log file is specified for a vhost, the log lines would go to the default log file (access_log).
On Red Hat flavors, start here and find out how those log files are specified.
- Dan Stoner