It all depends on your MOS. If you are something exotic and special you could be called up as an individual. Our Dustoff unit deploys in platoons.Different hammer, same nail.
We do things differently. Our TA / Army Reserve is a much more integral part of the full time Army with individuals slotting into roles. You guys are basically how the TA was before WW1.
Very separate organisations that operated under the own rules.
Gen question, as a National Guardsman, could you be called up as an individual, to slot into a regular Army unit, or do you go as a group with fellow Guardsmen?