One of the things which foreign tourists, or may be Japanese tourists get confused when traveling by train in Japan is that type of the trains are complicated.
Usually there are only 3-4 types of trains in Europe. EuroCity/InterCity, Express, fast and local trains excluding high speed trains such as TGV or Eurostar. On the other hand, Japan has limited express(特急), express(急行),rapid(快速), semi-express(準急),rapid express(快速急行),commuter express(通勤快速),commuter rapid(通勤快速), commuter semi-express(通勤準急) and local trains.
From fastest to slowest are in order - limited express > rapid express > express > rapid > semi-express. Commuter express, commuter rapid and commuter semi-express trains just run during rush hours, especially in the morning of weekdays.
Then, another confusing thing is that not all railway companies follow the same train types. For example, JR groups do not use semi-express at all and regular express trains are also abolished. Then, they do not use the word rapid express which is very common type of train of non-JR railway companies.
On the other hand, they use Special rapid which is 新快速 or 特別快速 is faster than normal rapid. Usually special rapid trains are second fastest trains of JR groups after limited express which you have to pay the additional fee.
Actually 新快速(pronounced as Shin-kaisoku) should be translated as New rapid, but JR changed the translation to Special rapid due to it does not fit the meaning. However, Shin-kaisoku itself is a weird meaning either.
By the way, if you are taking special rapid from Osaka station to Hikone station on JR Biwako line which is the nearest station of national treasure Hikone castle, please take the Special rapid A train. In case you take Special rapid B train, the train continues to Kosei line after departing Yamashina station in Kyoto.