What it really means
Открыва́ть is the broad, everyday imperfective verb “to open.” It applies to doors, windows, containers, books, accounts, events, and access: открывать дверь, книгу, выставку, or доступ. It focuses on making something accessible or no longer closed, and its perfective counterpart is откры́ть.
Раскрыва́ть has a more specific sense of opening something fully or spreading it apart, as with an umbrella, wings, a folded document, or a flower. It also means revealing a secret, explaining a meaning, or uncovering a crime. Use открыва́ть for ordinary opening; choose раскрыва́ть when the idea is unfolding, exposing hidden content, or opening wide.