They're both extinct bony fishes. The difference is that ostracoderms were jaw-less and placoderms had jaws.
Ostracoderms were ancient fish with an an armor of bony plates. However, your question is very muddled and therefore we can not answer it properly.
They were jawless fish that lived during the Paleozoic era Stunningly some of our oldest ancestors came from ostracoderms!
yes
Ordovician Period
They are any of several groups of extinct, jawless fish.
Yes that is true as sloss
placoderms (an ancient jawed fish)
comparison between Airbus380 & Airbus300
there is no comparison between them as far as i know
what is the comparison between Hubble telescope and Galileo telescope
Comparison happens after evaluation. Without evaluation ther is no comparison
primtie finsJAWSOstracoderms were jawless fishes with bony armor that protected them from predators.