Probably the most basic piece of information to understand when it comes to NVA and Grenztruppen uniforms is that there were conscript soldiers and career soldiers. The DDR had conscription until the end. Every able bodied male had to serve a minimum of 18 months in the armed forces. It was also possible to serve two years and three years as an extended service. Two years were some specialists, like paratroopers for example and three years were short term NCO's. All conscript soldiers had the woolly uniforms. Anyone serving more than three years (long term NCO's, Fähnrich and officers) was considered a career soldier and they had the Gaberdine uniforms. There were of course some exceptions with the Wachregiment units, Berlin Grenztruppen, etc. where conscripts also had Gaberdine uniforms as those guys were regularly in the public eye and had to look good.
First photo below is a Gaberdine jacket for career soldiers, in this case a Fähnrich Student. Second photo below is a woolly jacket for conscript soldiers, in this case an Air Force Soldat. Third photo is a paratrooper conscript serving two years, as indicated by the longer service chevron on the sleeve.