Aerospace & Defense companies can be defense contractors or commercial companies or both. Many companies such as Boeing provide both defense products (missiles, aircraft, electronics, etc.) as well as commercial products such as commercial aircraft or satellites.
Defense products include military aircraft, helicopters drones, tanks and other vehicles, ships and other marine vessels, as well as their unmanned counterparts. Also included are arms and ammunition, missiles, satellites, and related systems Military electronic systems include communications, information systems, intelligence, navigation, intelligence, computers/software and more. Estimating market size is dependent on how the segment is defined, so it is important to know what is and what is not included. Often the defense market is measured by military spending by country. Some country information are more reliable that others. There are always 'black' or secret programs but these are not included in publicly available data. Other factors play a role, such as foreign currency and valuation.
Aerospace Products can be a subset of Defense, when there are defense related, but this segment only include products that are aviation and space related they can be civil, commercial or defense.
In addition, there are service providers. These are companies who service products or provide parts and or services. An example can be a Maintenance, Repair or Overhaul (MRO) company. These can also be defense contractors, subcontractors to the government or commercial companies or both.
Some aerospace companies produce market reports, this is mostly for commercial products. You will find links to some of them below.
The list below includes very few investor presentations which can also be useful. You will find investor presentations under a company's main webpage in their 'investors' section, just Google the company name with investor Relations (e.g. Lockheed investor relations). It is hit and miss, some company's provide downloadable presentations, others may provide transcripts, audio or video.