THere is "true" convection and "fake" convection. I don't know if it is applicable to wall ovens but I learned about this when shopping for stoves several years ago.
True convection ovens have an additional heat source whereas the "fake" convection ovens just have a fan or something that blows the air around to distribute it.
Needless to say the stoves with the "true" convection were the priciest.
Some days I pray for Silence, Some days I pray for Soul,
Some days I just pray to the God of Sex and Drums and Rock 'N' Roll.