Both films examine questions about the meaning of family and the impact of money, through stories about a queer relationship across class differences in which one partner dies, leaving behind a partner and family members to grieve their passing.

Both films take a very figurative, "artsy", vibes-based approach to their narratives and themes, and both rely on subtle allusions to history. Both films place queerness (as a transgressive way of doing sexuality) in relation to migration and shadows cast by past conflicts, and both films do interesting things with temporality and spatiality.

In both films, the child of a queer parent unearths their parent's queer past by leaving home and, in doing so, changes the relationships around them in the direction of healing.

The overall plots of these two films have some interesting parallels and shared themes at a high level (including a story which bridges multiple decades of experience, a relationship between two high-schoolers which changes their relationship with a hostile world, and a separation which interrupts that relationship for a long time), and both locate their story in regionally-specific contexts. So Long, See You Tomorrow has less of the dramatic teenage angst of being a queer teen in a past decade (opting instead for a quieter form of teenage angst), a more meditative approach to its story, and a more hopeful and less bittersweet tone in its ending.