Approach: Compare the two protein classes point by point on shape, bonding, solubility and role.
Step 1: Molecular shape and chain arrangement.
In fibrous proteins the chains run parallel to one another and are stitched together into a rope-like fibre. In globular proteins a single chain wraps up on itself into a compact globe.
Step 2: Bonding and stability.
Fibrous proteins are stabilised by extensive hydrogen and disulphide bonds, making them tough and unaffected by moderate heat. Globular proteins are held by weaker interactions and denature (lose shape) more easily on heating or pH change.
Step 3: Solubility.
Fibrous proteins do not dissolve in water; globular proteins generally dissolve in water or dilute salt solutions.
Step 4: Biological function and examples.
Fibrous proteins are the building/structural materials of the body, e.g. keratin, collagen, myosin. Globular proteins do the active chemistry of life as enzymes, hormones and carriers, e.g. insulin, haemoglobin, albumin.
Conclusion: Shape (fibre vs sphere), solubility (insoluble vs soluble) and role (structural vs functional) are the key differences.