When selecting a potential trademark, it is important to minimize the risk of "likelihood of confusion" between your mark and an existing mark. The test for whether your mark is "confusing" with an existing mark (and therefore subject to potential rejection and/or challenges) is not simply whether the two marks are different when compared "side by side." The test is whether the two marks create the same overall impression, which is a much stricter standard and involves careful legal analysis.
Trademark- Likelihood of Confusion