With respect to the storyline, both the games are similar. Both of them are based in the Kanto Region. Essentially, both these games are remake of the Pokémon classics, Pokémon Red and Pokémon Blue. However, what differs is the version exclusive Pokémon available in these two games. In Fire Red, one can encounter Ekans, Oddish, Arbok, Gloom, Psyduck, Vileplume, Arcanine, Golduck, Shellder, Growlithe, Cloyster, Scyther, Electabuzz, Wooper, Bellosom, Scizor, Elekid,Murkrow,Delibird Qwilfish and Skarmory. On the other hand, the version exclusive Pokemon available in Leaf Green are Bellsprout, Sandshrew, Vulpix, Sandslash, Ninetales, Weepinbell, Slowpoke, Victrebell, Slowbro, Starmie, Staryu, Magmar, Marill, Pinsir, Azumarill, Magby, Slowking, Misdreavous, Remoraid, Sneasel, Octillery, Azurill and Mantine. Attack Deoxys is available in Fire Red during the events whereas Defense Deoxys is available in Leaf Green.
The player may also find some differences in the number of same Pokemon they might encounter based on the game they are playing ‘“ Fire Red or Leaf Green. For instance, the player may come across several male Nidorans in Fire Red whereas the chances of encountering these male Nidorans in Leaf Green are less. It is not possible to obtain all the Pokémon characters by buying either Leaf Green or Fire Red. If you are a Pokémon fan and want to obtain all of them, it is best you buy either Fire Red or Leaf Green and persuade one of your Pokémon friends to buy the other version of the game. Then both of you can trade the Pokémon you want. Pokémon fans have their own preferences ‘“ Fire Red or Leaf Green ‘“ based on the characteristics of the different Pokémon they can obtain in both the games. For those who own Pokémon Ruby, Sapphire or Platinum can revisit their Pokedex and then decide on which version to go for ‘“ Fire Red or Leaf Green.
Overall, these are the conclusions after a proper review of both the Fire Red and Leaf Green versions.
1.Essentially, both the versions are similar in storyline and challenges.
2.The basic difference is that each version has its exclusive Pokémon characters not available in the other version
3.There is also some difference in the rate and location or level at which the player comes across these Pokémon characters.