When we want to give an order or comand we use the Imperative. To represent this tense we resort to the figure of the general who gives orders and holds a baton or staff in his hand:
When we are not giving an order, but it is only an invitation, for instance, when we say Come to my house, etc, we do not pict the Order picto but the Invitation picto, represented by a man in the attitude of inviting someone: . This picto also means Invitation.
Let's take the sentence "I would go to France if I had money". My future trip to France is hanging or pending on the possibility of my having money. We can represent this situation with a hook from which the picto Future () hangs:
If we give a step further, we can make the picto for IF: