My original Fractal product was AXE-FX (2007?), then called Standard" when the Ultra was released ."Axe-Fx" is hyphenated...one word, followed by the numerical edition designator II, II XL, II XL+, III.
This. ^^^...Courts determine whether TM infringement exist based on a multi-factor test called "likelihood of confusion.". Each US Federal Circuit has slightly different factors, but the main ones are:
1. Are the marks "similar" (not identical" in sound, meaning, appearance, or overall commercial impression?; And
2. Are the goods/services of the parties "related" in purchasers, channels of trade, marketing channels, etc."
Also important is "strength of the mark" and third-party use of similar marks...