A large group of protesters are walking down the street with signs.
The group of protesters are ordering ice cream in a store.
The people can't be ordering ice cream in a store while walking down the street.
Walking down the street with signs indicates that the group is outside and participating in a common activity of protesters. Ordering ice cream in a store indicate the group is inside and participating in an activity that is not specific to protesters.
The group of protesters are either walking down the street with signs or ordering ice cream in a store.