SHA-224 and SHA-256 use 32-bit words and 64 rounds; SHA-384, SHA-512 and the truncated SHA-512/t variants use 64-bit words and 80 rounds. SHA-224 and SHA-384 are truncated versions of SHA-256 and SHA-512 with different initial values. Collision resistance is half the digest length: 112, 128, 192 and 256 bits for SHA-224, SHA-256, SHA-384 and SHA-512.
Choice in practice follows the algorithm it pairs with: SHA-256 with P-256, RSA-2048/3072 and HMAC (JOSE ES256, RS256, HS256); SHA-384 with P-384 (ES384, CNSA); SHA-512 inside Ed25519. Truncated variants (SHA-384, SHA-512/256) are not vulnerable to length extension, while full-width SHA-256 and SHA-512 are.
NIST IR 8547 (draft) keeps SHA-2 approved but lists SHA-224 at 112-bit collision strength, below post-quantum category 1, and says NIST's 112-bit symmetric standards will be disallowed in 2030.