The etiquette gap between generations inside a single culture can be wider than the gap between two countries, which is something expats discover quickly. Grandparents may expect formal address, unhurried visits, printed invitations, and deference in conversation; their grandchildren run on first names, group chats, casual dress, and open disagreement as a sign of engagement. Neither generation is wrong; each learned the code that fit its world, and each tends to read the other's code as either stiffness or disrespect.
Navigating this respectfully is mostly a matter of register-switching, the same skill you use across cultures. Match the formality of the person in front of you: fuller courtesy, patience, and traditional forms with elders; relaxed norms with peers. When hosting mixed generations, design for the most traditional guests present, since younger people flex downward far more easily than elders flex upward.