What is cat 3 vs cat 4?

Cat 3 vs Cat 4 comparison depends on context, but commonly refers to tractor hitch categories or safety categories or internet cables. In tractor three-point hitch, Category 3 vs Category 4 difference is size and power, Category 3 is for large agricultural tractors 80 to 225 horsepower with lower pins 1-7/16 inch diameter, top pin 1-1/4 inch, spacing 38 inches, lift capacity 5000 to 8000 pounds, used for heavy tillage like large plows for commercial farms. Category 4 is for very large tractors over 300 horsepower with pins 2 inch diameter lower and 1-3/4 inch top, spacing 46 inches, lift over 10000 pounds, used for biggest implements for large-scale farming, so Cat 4 is bigger and stronger than Cat 3. In safety categories per EN ISO 13849, Category 3 uses redundant dual-channel architecture where single fault does not cause loss of safety function with some diagnostics, while Category 4 provides highest safety with continuous monitoring and fault tolerance where accumulation of faults does not cause loss, used where failure could cause death. In networking, Cat3 cable supports 10 Mbps, Cat4 supports 16 Mbps for token ring, both obsolete compared to Cat5e and Cat6. In aviation, there is CAT III but no CAT IV for landing, CAT III is highest with zero visibility. So generally Cat 4 is bigger, stronger, or safer than Cat 3, representing highest tier in each system, requiring more robust design and offering greater capability.