The analogy between presentism and actualism has often been noted.  An unpacking of the analogy may prove fruitful if it doesn't perplex us further.  Rough formulations of the two doctrines are as follows:

P. Only the (temporally) present exists.

A. Only the actual exists.

Now one of the problems that has been worrying us is how to avoid triviality and tautology.  After all, (P) is a miserable tautology if 'exists' is present-tensed.  It is clear that the typical presentist does not consider the thesis to be a tautology. It is also clear that there is a difference, albeit one hard to articulate, between presentism and the various types of anti-presentism.  Consider the difference between presentism and eternalism. The presentist holds that only present items exist whereas the eternalist holds that past, present, and future items exist.  The disagreement obviously presupposes agreement as to what is meant by 'exists.'   There is a substantive metaphysical dispute here, and our task is to formulate the dispute in precise terms.  This will involve clarifying the exact force of 'exists' in (P).  If not present-tensed, then what?

A similar problem arises for the actualist.  One is very strongly tempted to say that to exist is to be actual.  If 'exists' in (A) means 'is actual,' however, then (A) is a tautology.  But if 'exists' in (A) does not mean 'is actual,' what does it mean? 

We seem to have agreed that Disjunctive Presentism is a nonstarter:

DP.  Only present items existed or exists or will exist.

This is equivalent to saying that if x existed or x exists or x will exist, then x presently exists.  And this is plainly false. Now corresponding to the temporal modi past, present, and future, we have the modal modi necessary, actual, and merely possible.  This suggests Disjunctive Actualism:

DA.  Only the actual necessarily exists or actually exists or merely-possibly exists.

This too is false since the merely possible is not actual.  It is no more actual than the wholly future is present.

We must also bear in the mind that neither the presentist nor the actualist intends to say something either temporally or modally 'solipsistic.'  Thus the presentist is not making the crazy claim that all that ever happened or ever will happen is happening right now.  He is not saying that all past-tensed and future-tensed propositions are either false or meaningless and that the only true propositions are present-tensed and true right now.  The presentist, in other words, is not a solipsist of the present moment. 

Similarly with the actualist. He is not a solipsist of this world.  He is not saying that everything possible is actual and everything actual is necessary.  The actualist is not a modal monist or a modal Spinozist who maintains that there is exactly one possible world, the actual world which, in virtue of being actual and the only one possible, is necessary.  The actualist is not a necessitarian.

There is no person like me, but I am not the only person.  There is no place like here, but here is not the only place.  There is no time like now, but now is not the only time.

In sum, for both presentism and actualism, tautologism, disjunctivism, and solipsism are out! What's left?

To formulate presentism it seems we need a notion of tenseless existence, and to formulate actualism we need a notion of amodal existence (my coinage).   

We can't say, on pain of tautology, that only the present presently exists, and of course we cannot say that only the present pastly or futurally exists.  So the presentist has to say that only the present tenselessly exists.  

What do I mean by amodal existence?  Consider the following 'possible worlds' definitions of modal terms:

Necessary being: one that exists in all possible worlds
Impossible being: one that exists in no possible world
Possible being: one that exists in some and perhaps all possible worlds
Contingent being: one that exists in some but not all possible worlds
Merely possible being: one that exists in some possible worlds but not in the actual world
Actual being: one that exists in the actual world
Unactual being: one that exists either in no possible world or not in the actual world.

In each of these definitions, the occurrence of 'exists' is modally neutral analogously as 'exists' is temporally neutral in the following sentences:

It was the case that Tom exists
It is now the case that Tom exists
It will be the case that Tom exists. 

My point, then, is that the proper formulation of actualism (as opposed to possibilism) requires an amodal notion of existence just as the proper formulation of presentism requires an atemporal (tenseless) notion of existence.

But are the atemporal and amodal notions of existence free of difficulty?  This is what we need to examine.  Can the requisite logical wedges be driven between existence and the temporal determinations and between existence and the modal determinations? If not then presentism and actualism cannot even be formulated and the respective problems threaten to be pseudo-problems.