Is there a difference between pneumonia and walking pneumonia?

Not really: One just means you are not hospitalized and lying in a bed . . . I.E., walking. However, pneumonia is the same, although perhaps caused by different organisms or bugs -- which may affect you more than someone else.

Atypical pneumonia.: "Walking pneumonia" is an older term for what we now call atypical pneumonia, that which is caused bacteria that we don't typically find in cases of pneumonia. These bacteria tend to cause milder versions of pneumonia, so you feel sick but not REALLY SICK, so you tend to "walk" around with your pneumonia not realizing you actually have pneumonia that requires treatment.

Implication: The core definition is the same. It is an infection of the lung. Some practitioners add the extra word to imply you can treat it at home.

Second is a type : Pneumonia. The later specifies that the infection was acquired in the community and person not very sick. Another form of pneumonia will be hospital acquired