I don´t know how detailed you want to have the answer. The eagle is the standard insignia for all brnaches of the Wehrmacht and Waffen-SS. The different branches (Army, Navy, Air Force) had different styles of eagles which differed in details and position. Waffen-SS members had the eagle on the left upper sleeve, Wehrmacht members on the right breast. All headgear also showed the eagle as standard symbol.
Reserve Officers were officers which received their officer training before the war and were sent from active to reserve status to be available when needed in times of war for example.
The "bars" on the collar were different with officers and lower grades and showed the colour of arms which means different colours for armoured troops, infantry, artillery etc...
This is a very basic, simplified answer. Don´t hesitate to ask for more details.