Hi Markie Boy,
Thanks for the questions and an honest openness to whatever Truth may be! We’re glad to have you here.
Here’s a simple breakdown of the words…
Consubstantial: con, “with,” substantial, “substance”
Transubstantial: trans, “change,” substantial, “substance”
The Son (and Holy Spirit) are consubstantial with the Father, since they are all “with the same substance,” that substance being God. Each Person of the Trinity is God, though we say they are distinguished “by relation,” which is a discussion perhaps for another day.
Lutherans, for example, believe in a consubstantial Eucharist… Jesus becomes one substance with the bread, so to speak, in that he is in, with, around that substance of bread, but there remains the actual substance of bread (and wine).
Catholics say that the substances of bread and wine are annihilated during the consecration, such that only the substance of the flesh and blood of Christ are present (together with the other elements of the Eucharist, which are His Soul and Divinity). In fact, we say the whole Christ (Body, Blood, Soul, and Divinity) is under each form, or species (the bread/wine distinction, which we now call the “accidents” of bread and wine due to their retaining their shape, color, smell, taste, etc., as opposed to the “essence,” or fundamental being, OR SUBSTANCE of bread or wine).
And we say this not only because of this being the persistent tradition, but also because it is also the plain meaning of Christ’s words, “This is my body… This is my blood.” If God can truly become a man, certainly that man can truly become like food and drink.
Does this help?