Short answer: pick iPhone 17 Pro Max if you want the biggest screen, the longest battery, the best telephoto/zoom and maximum storage; pick iPhone 17 Pro if you prefer something easier to hold, slightly lighter, and want most Pro features for $100 less. Below are the concrete differences and which one makes sense for common buyers.

Key differences (high-level)

• Size and display: iPhone 17 Pro = 6.3" Super Retina XDR; 17 Pro Max = 6.9" Super Retina XDR. Larger screen on the Pro Max for media, gaming and reading. (Apple.com)
• Battery: 17 Pro Max has the best battery Apple has shipped — roughly up to 39 hours video playback vs up to 33 hours on the 17 Pro (Apple’s advertised numbers). Expect substantially longer real‑world uptime on the Pro Max. (Apple.com)
• Camera: both share the new 3×48MP “Fusion” camera system, but the Pro Max includes the longest optical-quality zoom (8× equivalent) and the largest physical camera array — better for telephoto and low‑light tele work. Both gain pro video features. (Apple.com)
• Performance and features: same A19 Pro chip and most software/features (Apple Intelligence, ProMotion 120Hz, Ceramic Shield 2, Wi‑Fi 7 with N1 chip, etc.). (Apple.com)
• Storage and price: iPhone 17 Pro starts at $1,099 (U.S.) with 256GB; iPhone 17 Pro Max starts at $1,199 (U.S.) with 256GB and can go up to 2TB. So base price difference is ~$100. (Apple.com)
• Durability and design: both use the new aluminum unibody and Ceramic Shield 2 front (and Apple says the back uses Ceramic Shield for better crack resistance). The Pro Max is heavier and bigger to pocket and one‑hand use. (Apple.com)

Who should get the iPhone 17 Pro Max

• You watch a lot of video, play graphically intense games, edit video/photo on the phone, or want the longest possible battery life.
• You want the best telephoto zoom and largest storage options (2TB).
• You don’t mind a larger/heavier phone and want the biggest display.

Who should get the iPhone 17 Pro

• You want most Pro-level performance and cameras but prefer a more pocketable, lighter phone and easier one‑hand use.
• You want to save about $100 off the base price but still get top-end features and very strong battery life.
• You don’t need the longest optical zoom or the absolute largest display.

Other practical considerations

• If you plan to keep the phone multiple years, the Pro Max’s battery and telephoto advantages are more future‑proof — but weight and daily comfort matter.
• Check carrier and trade‑in promotions: often trade‑in deals or carrier offers can narrow the effective price gap. Apple preorders began Sept 12 and units became available Sept 19, 2025. (Apple.com)

Quick recommendation by user profile (one‑line)

• Heavy media/gamer/creator or need max battery & zoom → iPhone 17 Pro Max.
• Everyday user who wants top performance in a more comfortable size and lower cost → iPhone 17 Pro.

If you want, I can:

• Compare exact weights and dimensions, or list pros/cons for a specific use (commuting, pockets, camera priorities), or check current carrier trade‑in deals to see which offers the better effective price.