depends on the weather outside and how skilled the grower is and the seasons. there could be different results for different growers, season, and good/bad weather. like say it was cold outside. you planted a seed outside adn one inside on the same day. the plant inside grows while the plant outside grew than died due to weather. there u go, in that case inside grew better. also say that you planted 1 seed outside and 1 inside on the same day. You have poor lighting and split your plants alot. while outside its june and weather is great. you know whic one grows faster then......

hope i helped please excuse the THC content in my boday at this time lol.