What distinguishes the sleeve device of an O-2 from that of an O-1?

The distinguishing feature of the sleeve device of an O-2 compared to that of an O-1 is the quarter inch gold stripe above the insignia. For officers, the rank insignia is often defined by the number and type of stripes or bars present on the sleeve.

In this instance, the O-1 rank, which is often referred to as a Second Lieutenant or equivalent, typically has no stripes above the insignia. The O-2 rank, such as a First Lieutenant, is denoted by the addition of a quarter inch gold stripe above the insignia. This slight yet significant detail makes it easier to identify the advancement in rank visually.

The other options presented represent different configurations of stripes or bar insignia that do not apply to the distinction between O-1 and O-2 ranks; thus, they do not represent the specific characteristic that differentiates the two ranks in terms of sleeve devices.