Haynes manuals will cover engine, gearbox, running gear, braking and (to a great extent) electrics: Interior details will be different and bodywork is obviously not the same.
3727 covers
Golf Hatchback and Estate and Bora Saloon, inc. special/limited editions, April 98 - 00, R to X
Petrol: 1.4 litre (1390cc), 1.6 litre (1595cc), 1.8 litre (1781cc)(includes AGN) and 2.0 litre (1984cc) 4-cyl, inc. turbo
Diesel: 1.9 litre (1896cc)(includes AHF and ASV) inc. turbo-Diesel
Does NOT cover 4-Motion (4x4) or Cabriolet
Does NOT cover 2.3 litre V5 engine
Does NOT cover 1.9 litre 'PD' engine
4169 covers
Petrol: 1.4 litre (1390cc), 1.6 litre (1595cc & 1597cc)(includes AEH & AKL), 1.8 litre (1781cc)(including AUQ)& 2.0 litre (1984cc) 4-cylinder, inc. turbo.
Diesel: 1.9 litre (1896cc)(includes AHF & ASV and ARL) , inc. turbo
Does NOT cover 2.3 litre V5, or 2.8 or 3.2 litre V6 petrol engines.
Does NOT cover V5, 4-Motion, R32 or Cabriolet models, or new Golf range introduced January 2004