EVM addresses and the capitalisation trick
An EVM address is twenty bytes shown as forty hexadecimal characters. The mixed capitalisation you see is not cosmetic — it encodes a checksum, so a wallet can detect a mistyped character that would otherwise look valid.
An all-lowercase address is still accepted by most tools, which means the check is skipped. Preferring the checksummed form is a free safety margin.
Why the same address works on many chains
Every EVM network derives addresses the same way, so one key produces the same address on Ethereum, BNB Chain, Polygon, Arbitrum and the rest. This is convenient and is also the source of the worst mistake in crypto.
The address being valid on the destination chain does not mean the token exists there or that anyone controls it there. Sending a token to a correct-looking address on the wrong network usually means it is gone.
Solana is a different format entirely
Solana addresses are base58-encoded 32-byte public keys — no 0x prefix, mixed case by nature, and typically 32 to 44 characters. An EVM address is not valid on Solana and vice versa.
Solana also has associated token accounts, so the address you send a token to is derived from your wallet address and the mint. Wallets handle this, but it is why a token balance can need an account created before it can be received.
Habits that prevent the permanent mistake
Verify the first and last several characters and at least one group in the middle — address poisoning attacks specifically target people who only check the ends. Send a small test amount for a first transfer to a new destination.
Confirm the network on both sides, every time. FBT Swap shows the selected network before each signature for exactly this reason.