Well, I would say that jhana results in samadhi. There are other examples in the sutras. One that I recall well is the exchange in the Parinirvana Sutra with Pukkusa when the Buddha relates a time when he sat through a lightning storm and didn’t hear or see any of it because he was in meditation. When he’s asked if he was conscious (saññī) at the time, he replied that he was. He told that story after Pukkusa tells the story of Alara Kalama sitting through a five hundred cart convoy rumbling by next to him without noticing it.
At the conscious level of vijnana. There is no conscious awareness of something if vijnana isn’t giving it attention. Sanna is not this function of awareness; it’s a tool that vijnana uses to recognize things. It processes raw input from the senses into concepts and imagery. The word is often used for those concepts and images, not just the function of mind that creates them.
But conscious awareness is vijnana, and it’s attention directed at a small portion of the sensory field at any given moment. We become aware of where we direct our attention, but it floats around freely from one sense to another when we aren’t focused on something, which gives the impression of being aware of everything at once. When attention first lands on something, the initial experience is vitakka. If it stays there and examines it, that’s vicara. Most exegesis characterize vitakka as initial and crude, and vicara as subsequent and increasingly refined, like the sound of a bell.
The concrete example of this I like to use is seeing an animal run across a footpath. In the initial moment of recognizing it, it’s mostly a blur. It has a vague size and color, maybe we notice that it’s furry or scaly. But it takes a moment or two of attention to recognize that it’s a squirrel or a lizard. Longer than that to recognize what particular species of squirrel or lizard that it is (which also requires knowing how to identify the species). The animal will need to stop in front of us long enough to do that. But it’s quite possible to not even notice the animal at all. We have to actually give it that initial attention or recognition to be aware of it.
I’ll give another example that’s clearer: Sometimes while I’m concentrating on translating Chinese, my wife appears in my doorway and starts talking to me. Now, I do notice that she’s standing there and talking, but if I don’t stop working and give her my full attention, I won’t “hear” anything that she’s saying to me. Which, embarrassingly, happens sometimes. When I realize, “Oh, I didn’t hear any of that,” I stop and ask her to repeat herself. She’s standing two feet away from me, and I have excellent hearing. But I’m stuck in visual and mental vijnana in front of a computer and not paying much attention to what I’m hearing. I.e., I’m not aware of the actual words being said. There’s only a vague awareness of someone talking. The Buddhist way of thinking about it is that my attention doesn’t stay on what I’m hearing long enough to recognize words. It’s skipping back and forth, staying mostly on what I was doing before she arrived, so there is only a vague awareness of the situation.
In these examples, sanna is not the awareness of something, but the image that’s formed immediately upon sensing it. That image is matched to what we already have experienced or learned. Recognition takes place when the closest match is made, and the concept that it matches usually has a verbal name. In the footpath example, it might be “red squirrel,” though maybe at first it’s just “animal.” There would probably be multiple matches happening in quick succession: It’s an “animal,” then a “mammal,” then a “squirrel,” then a “red squirrel,” maybe it even reaches the level of “an adult female red squirrel that’s well-fed and healthy-looking.” It takes time for that to process of refined recognition to happen. This is what vicara describes. Like the sound of the bell, it becomes more and more fine.
An easier way to notice the unconscious sanna process is when it goes wrong. Sometimes, the sensory image is matched to the wrong concept in our memory, and it’s confused for something else. The wrong thing replaces it in our experience, becoming like an hallucination. I remember a time when I was driving at night and saw a piece of farm equipment in front of me, lit up with a bunch of lights. It was too dark to see it’s shape. For a few seconds, what I “saw” was a UFO hovering over the road. There’s also the traditional example in ancient texts about mistaking a rope for a snake. Usually, those hallucinations don’t last very long, but they happen. It indicates that there’s an unconscious process of sanna-making, but we’re only aware of it’s end result. Vijnana isn’t directly aware of raw sensory data; it works with the sanna that’s formed from it.
This is how I understand the use of these words, at least. It’s largely a generalization of how they were used by various Buddhist traditions, so it’s likely to not entirely agree with any one in particular.