The SK-1 was the spacesuit worn on the Vostok 1-5 flights.
The same article describes the SK-2 suit as "[a]lmost exactly the same as the SK-1 but designed for a woman". It was worn by Valentina Tereshkova -- the first woman in space -- on Vostok 6.
What are the actual differences between the suits?
The SK-2 suit differed from the SK-1 suit mainly in the enclosure cut-out that took into account the specific features of a female body. The enclosure featured a decreased shoulder breadth, an increased hip girth and a decreased opening in the neck partition. In accordance with the decreased shoulder breath, the restraint system of shoulder joints was modified to retain arm mobility.
Moreover, the position of the cord that kept the helmet at the front was changed. It was moved down from the breast. The gloves were also modified. The thickness of the thermal protection layer was decreased and mobility of the thumb improved. The lever for opening the respiratory valve and handles on the visor were modified to improve reach and make them handy. The required changes were also introduced in the design of the receptacle of the waste management system.
Source: Russian Spacesuits by Isaak P. Abramov and A. Ingemar Skoog
