"gives the perfect opportunity to discuss what the difference is between an astrological talisman and a planetary talisman is. Is there actually a distinct difference?"
As I was writing the post, a similar thought occurred to me.
Before we jump right into the discussion, let's talk about talismans in general. I find the best way to understand the role of a talisman is to think of it as the body of the spirit it represents. It's like a Golem, but it doesn't (necessarily) move, or terrorize Prague. You're creating a physical form in your material reality through which the spirits, intelligences, or forces you're working with can manifest.
Next let's talk about astrological influences. We look at the positions of the stars and planets relative to our birth time and location to get an insight into the forces and fates that will influence our experiences throughout our lives. The natal chart in the hands of a trained astrologer can be a scary thing, as a complete stranger sits there telling you what kinds of things have happened to you for the last thirty years, and what to expect going forward.
When we create talismans based on astrological influences, we're looking for the best possible "natal chart" for our created entity, one that harmonizes with our desired intent. If you think of a talisman as a living entity, it's easier to understand. We're picking out its Natal Chart, and we want it to be powerful and successful in specific areas.
Turning to planetary vs. astrological talismans, I hesitate to make a distinction between the two. If you're making a general "Jupiter Talisman" to capture and radiate the forces of Jupiter based on his astrological position in the sky, it's an astrological talisman. You're aiming to capture the forces of the moment. The stuff you put together becomes a body, and the consecration ensouls it, the same way God ensouled Adam with his breath. That entity will continue to work on your behalf as long as it has a body.
However, if you're making a Tzadkiel Talisman, or a Jove talisman, or a Jupiter-the-Roman-God talisman, it's not exactly the same thing. These are spirit talismans, primarily. There's an active, pre-existing spirit that will be working through this particular body. Jupiter-the-God is an intelligent, self-aware, proactive being who has access to a wide range of spirits and forces that he can direct on your behalf (or against you if you piss him off). A talisman of Jupiter-the-God is not simply a snapshot of the forces of the planet at the time it was made.
But you have to remember that everything manifest in the material world is still influenced by the astrological factors at the time it was created. If your natal chart leaves you with a predisposition to be lazy, you can still work hard, you just have to overcome that tendency. Likewise, a spirit talisman created at an inauspicious time creates a certain inertia that will have to be overcome every time it is used to manifest the forces of the Spirit it represents.
This is why Agrippa says you can't ignore the astrological conditions of any magical activity. Again, I like the weather analogy. Suppose you want to have a snowball fight. You want to do it right now, because it's an awesome idea, right? But you're living in Texas, and it's the middle of July. There's no snow. You REALLY want that snowball fight, so you get some water, freeze it, shave it, blow the snow into the protected air conditioned closed environment, and invite your friends in, and you have the snow ball fight for as long as possible.
It's not the same as having a snow ball fight in January in Canada, but it's still a snowball fight.
So yeah, astrological influences can be overcome if you try hard enough. There are two ways to empower a talisman, as Christopher Warnock said in a comment on a post of mine a while back, you can do it when the astrological timing is right, or you can consecrate the fuck out of it. Most of my spirit talismans are made during the appropriate planetary hour of the appropriate planetary day, preferably at dawn when the Sun's rays can be used to boost the forces at hand. These spirit talismans rely primarily on the Spirit's power and innovation to overcome any negative astrological influences, and it works well enough for most of my Hermetic Work.
But it's like giving the spirit a crippled body to work through if you don't take into account the astrological forces. Yes, people in wheelchairs can overcome handicaps to achieve great things, but why put them in that position in the first place?