Feedback activity is for asking questions (feedback). You can use it anonymously or with names
Results can be shown to all participants or can be restricted to teacher only.
There are several question types: multiple choice, yes/no or text input
Use for: collecting feedback after a lesson, ask if something was difficult etc
With a questionnaire activity, teacher can create a survey and collect data from students, anonymously or with names.
Many types of questions: scales, multiple choice, radio buttons, yes/no, text box etc. Result can be shown to all participants (statistics).
It can be answered once or several times, students can see all their answers.
Use for: a survey in the beginning and in the end of the course