Yes, algebraically, the equivalent form and the relative form are interchangeable or "accidental":

Whether, then, a commodity assumes the relative form, or the opposite equivalent form, depends entirely upon its accidental position in the expression of value – that is, upon whether it is the commodity whose value is being expressed or the commodity in which value is being expressed.

The difference between the forms is purely semantic. If I exchange 5 apples for your 3 oranges, that is a value relation. I am equally correct in saying that your 3 oranges express the value of my 5 apples, as you are correct in saying that my 5 apples express the value of your 3 oranges. Each statement is correct but the meaning is different. The equivalent form is the commodity which expresses value, whereas the relative form is the commodity whose value needs expressing. It seems like a trivial distinction at first, but its significance is in the emergence of the money commodity. If any commodity can take on the role of the equivalent form, then it follows that one particular commodity may in practice take on the role of universal equivalent. This is money. And in its full development, we do not regard money in its relative form; we regard money as a pure embodiment of value, as being value in itself, and not needing to express its value in another equivalent.

Since the relative form of value of a commodity – the linen, for example – expresses the value of that commodity, as being something wholly different from its substance and properties, as being, for instance, coat-like, we see that this expression itself indicates that some social relation lies at the bottom of it. With the equivalent form it is just the contrary. The very essence of this form is that the material commodity itself – the coat – just as it is, expresses value, and is endowed with the form of value by Nature itself. Of course this holds good only so long as the value relation exists, in which the coat stands in the position of equivalent to the linen. Since, however, the properties of a thing are not the result of its relations to other things, but only manifest themselves in such relations, the coat seems to be endowed with its equivalent form, its property of being directly exchangeable, just as much by Nature as it is endowed with the property of being heavy, or the capacity to keep us warm. Hence the enigmatical character of the equivalent form which escapes the notice of the bourgeois political economist, until this form, completely developed, confronts him in the shape of money.