Ok thanks for the explanation. In WPAdverts the get_avatar() function is used to display use profile photo, but it does not use the email entered in user profile to get the avatar but rather the email address entered in Contact Email field in the [adverts_add] form.
This is because in WPAdverts not logged in users can post Ads as well, so it is possible there will be no user account associated with the Advert.
Right now the only way to change that is to open file wpadverts/templates/single.php and change the line
<?php echo get_avatar( get_post($post_id)->post_author, 48 ) ?>
to
<?php echo get_avatar( get_post_meta($post_id, 'adverts_email', true), 48 ) ?>
In the next release, we will make an update that will first look for the user id and then for the contact email. If all your users posting Ads are registered then this should give you the same avatars for WPAdverts, forums and chats.