Japanese seems to have a range of words for the English words "implement" and "capacity", depending on the situation. What are the differences between these words?
Each kanji tells its meaning.
実装: Because 装 means "mount" or "install", the word means implementing something on machines (hardware and software) for it to work.
実施: 施 means "exert" or "extend", so the word is for implementing rules, strategy, or activity to make people act in some ways. It does not translate such "implement" for all situations. This one is for something mainly affecting other people than the planner; 実行 is better for what yourself mainly do; 遂行 if it is a task rather than your initiative; 履行 if promise; and so on.
社会調査を実施する conduct a social survey
オリンピックを実施する Olympic Games take place (rather than not)
実現: 現 = "appear; be present". I don't think it corresponds to "implement" in many cases. Its core meaning is "materialize" or "fulfill", so if something is "implemented", it is probably "materialized" too. As an aside, the reversed 現実 is totally different thing "reality".
容量: 容 = "contain", 量 = "mass". Thus it means how much bulk, such as those of wheat or water, a container can hold, but also by extension, data (of storage) or people (of building) etc.
体積: It means volume, which is 体 = "cubic", 積 = "expanse".
容積: 体積 a container has inside. Of course it is equivalent with 容量 under the scientific definition, but rather focused on how much space (physical only) it has.
PS: If you ask about a server machine's 容量, I'd likely answer in bytes. If its 容積, likely in liters or cubic meters.
