The parade stops feature the characters waving gold banners and doing a choreographed routine to a specific point in the music. The parade stop can be a fun time for character interaction, but not a good time for getting a picture with the character like you would at a meet and greet. You can only take pictures of the characters during the parade. The only way you might be able to take a pic with a character would be if your child was sitting on the sidewalk when the character walked by and started talking with your child. You would not be able to stop the parade and have them pose for the picture, but only take a picture of them talking.
For instance, Ariel remains on her float the entire time, so while she may notice your child and talk with her during the show stop and/or as the parade goes by, there's no way you could get a pic of both your child and Ariel during the parade. The first 3 Disney princesses briefly get off the Sleeping Beauty Castle float to walk around it, but they don't stop to take pictures with guests.
If your child only has to see certain characters, the parade is a good way to so without waiting lengthy periods of time to do so. Disneyland's parade features some(but not all characters) from Peter Pan, Pinocchio, Beauty and the Beast, The Little Mermaid, Alice in Wonderland, The Lion King, Snow White, Cinderella, Sleeping Beauty, and the Fab 5(no Daisy) along with Chip and Dale. If your child wants to meet, interact with, get a picture taken with, and possibly get an autograph from a certain character, a meet and greet/character meal is the only way to go.
I asked about this a week or two ago, when my 3 year old started her Peter Pan kick. 
