When someone has an expanding energy, it seems like they are "reaching out to the world".
Sensors see the world much more clearly than Intuitives; not necessarily literally (when it comes to eye sight), but in certain ways, they do. At least their strength is focused on the material world. Se ego types have that energy of "constantly reaching out", or being on the verge to. Mentally, it is like they constantly go around with a hand reached out, ready to catch any ball that is being thrown at them, or ready to pick up any cup from any counter. With Intuitives, it is like they don't even see the cup or ball (especially for Ni leads, haha).
I'd say Si ego types see the ball coming too, but they feel less inclined to catch it. If they don't feel like it for whatever reason, they would just avoid it and step aside. They may reach for the cup and drink what's in it, because they know what it is, and they feel like it would benefit their inner harmony, its particular taste will be very pleasant. The Se type may be drinking from the cup just to have something to do and see what's in it; there are not "fussy" with their objects and senses like Si users tend to be.
So, imagine a room with 4 different people in it.
Person 1 is reaching out all the time, or has that "ready-go" attitude. Throw a ball at them, they catch it immediately. They would be the Se lead.
Person 2 seems like they can hardly see, or "have blinds on". Throw a ball at them, and they get hit. They would be the Ni lead.
Person 3 may look like they are reaching out a lot, like Person 1, based on how curious, but scatterbrained they seem. Throw a ball at them, and they may attempt to catch it, but are more likely to miss it. You thought they were ready, but they weren't actually. They would be the Ne lead.
Person 4 has a relaxed attitude and looks like the regular observer of situations. Throw a ball at them, and they may either catch it reluctantly or step aside, so it flies past them. They would be the Si lead.
These people were the "extreme" of each perceiving IE. Those who have a perceiving IE as their Creative function may relate to those people the best if they are the Contact subtype, and the least if they are the Inert subtype. For instance, an ESI-Se will relate to Person 1 rather easily. While ESI-Fi may not as much.