First edition is just a stamp put on the card that signifies it was printed on the literal first batch of that set. Every other print they ran after is not part of the “first run” so it doesn’t have the stamp. Doesn’t matter if they are printed in the same year… it doesn’t take that long to print them xD
Most early WOTC Pokemon sets had two official printings, 1st Edition, a limited production run that had less to do with demand and was typically a smaller percentage of the total cards printed, and Unlimited (your card), the remainder of the printing that was “unlimited” in that this was the rest of the printing through the sets production and distribution. The official numbers have never been released but there are for sure less 1st Edition out there than Unlimited. It makes 1st Edition more collectible and desirable but there’s nothing wrong with collecting Unlimited. It’s what most kids had and the market is well-established for both in most cases. As mentioned above, if your card was from a 1st Edition pack the only difference would be the stamp on both the packs it came from and the card.
Some early WOTC sets such as Base 2, Legendary Collection, and E-series did not have a 1st Edition counterpart.
The most interesting and wide differentiation between 1st Edition and Unlimited is with Base Set. Not only are 1st Edition Base cards far more limited when compared to their Unlimited printing than a set like Jungle but the entire card template changed from the “Shadowless” design to the well-recognized Unlimited template with variation in color, text, drop shadow, etc.