In our Family Matching algorithm, the number of matching segments is weighted more heavily than the overall length of segments, but this rule only applies over 2nd-4th cousins.
This means that if you have two matches with the same total cM value, but one has two segments and the other only one, then it is more likely that the former is a closer relative
The more segments you match with the closer you are related, but this is only the case when considering more distant relatives. It's not quite the same for Parent/Child and Full Sibling relationships. The number of segments is taken into account by our Relationship Distance Estimation method (ERSA).