The primary differences between loin ribs (often called baby back ribs) and spare ribs lie in their location on the pig, their size, meat content, and flavour profile.

Loin Ribs (Baby Back Ribs):

1. Location: Loin ribs are taken from the top of the rib cage, near the spine, below the loin muscle. They are called "baby" because they are shorter and smaller compared to spare ribs.
2. Size and Shape: Loin ribs are shorter, curved, and meatier. They typically have a higher meat-to-bone ratio.
3. Meat Content: The meat on baby back ribs is leaner and more tender since it comes from a less worked muscle area.
4. Flavour: They have a milder flavour compared to spare ribs, often considered more tender and juicy.
5. Cooking Time: Due to their smaller size and leaner meat, baby back ribs usually cook faster.

Spare Ribs:

1. Location: Spare ribs are cut from the lower part of the rib cage, near the belly. This area includes the breastbone and the cartilage.
2. Size and Shape: Spare ribs are larger, flatter, and have more bone and connective tissue.
3. Meat Content: They have more meat between the bones rather than on top, and this meat tends to be fattier and tougher.
4. Flavour: Spare ribs have a richer, more intense flavour due to the higher fat content and the location of the ribs.
5. Cooking Time: They require longer cooking times to become tender due to their size and the higher amount of connective tissue.

Summary:

• Loin Ribs (Baby Back Ribs): Smaller, leaner, more tender, milder flavour, quicker to cook.
• Spare Ribs: Larger, fattier, tougher, richer flavour, longer cooking time.

Both types of ribs are popular for barbecuing and can be delicious when prepared properly, with the choice often depending on personal preference for flavour and tenderness.