When filing for a Federal trademark, it's important to keep the SAM rule in mind.
SAM's not a person but a concept employed by the USPTO during their review process of new Federal trademark applications.
The USPTO will refuse registration "if the marks are similar and the goods and or services related." So basically marks do not need to be exact conflicts to be considered for refusal. ""Similarity in sound, appearance, or meaning may be sufficient to support a finding of likelihood of confusion," hence the SAM rule.
Let's take some time to dissect the first one – SOUND
Similarities in sound takes into consideration that consumers often hear trademarks be it on television, radio, podcasts, etc. Because of that the USPTO will take into consideration marks that SOUND similar to one another.
Let's look at an example to illustrate this point.
You have a clothing line you want to trademark Federally called DestinyDesigns. The comprehensive research you ordered showed a registered trademark for clothing for Destiknee Dezines. The spelling is wildly different but when you say both, they SOUND identical.
*Comprehensive research will be on the lookout for SAM*