Who is that smiling girl? (present participle)
The exhausted runner dropped to the ground. (past participle)

Note that the nounA part of speech that names a person, place or thing. E.g.: The koala is a marsupial. ("koala", "marsupial") modified by the present participle in the first sentence is the doer (or agentThe doer of an action; the person or the thing that does something. E.g.: True Romance was written by Tarantino. ("Tarantino")) of the actionA general term expressing that somebody or something does something (the girl is smiling), whereas in the second sentence the past participle shows what happened to the modified noun (the runner was exhausted).

The perfect participle replacing a clause
The use of participles The present participle replacing a clause