Is Clarity more recent and higher res? The ESRI description isn't exactly clear.
From the description of the World Image (Clarity) map service:
This tile layer is designed to present imagery from our archive that may be more clear and/or accurate than what is presented in our default World Imagery map.
The World Imagery map is designed to present our most recent, high-quality imagery available.
That's the second link you posted with the standard World Imagery service. The Clarity imagery service on the other hand prioritizes clear, accurate images which may or may not be as recent as those in the standard image service.
This layer presents an alternative view, enabling users to access imagery from our archive that may not be otherwise be available. The imagery in this view may be less current than the default imagery (e.g. more than 3-5 years old), but support use cases (e.g. data collection) where the image clarity or accuracy is more important. In areas where the most recent imagery is also the clearest and/or most accurate available, the same imagery will be presented in both views.
Which one will be most useful for your analysis depends on exactly what you require. Do you need the most recent imagery or the most clear imagery available?