"Learn on the go" has a connotation of moving or using "downtime" effectively, whereas "learn on the fly" suggests a more immediate and pressing need to adapt.

Both "learn on the fly" and "learn on the go" involve learning without traditional or prolonged instruction.

As a startup founder, Jennifer had to learn on the fly about different aspects of running a business.

With her busy travel schedule, David always relied on language apps to learn on the go.

However, "learn on the fly" suggests a more immediate and pressing need to adapt and pick up new knowledge or skills.

During the software upgrade, several unexpected issues arose, forcing the team to learn on the fly and come up with solutions.

"Learn on the go", by contrast, has the connotation of multitasking, utilizing "downtime" effectively, or learning while moving or being active.

Podcasts allowed Olivia to learn on the go, making the most of her daily commute.