Ruminant meats (beef, lamb, goat) have a higher GHG impact due to enteric fermentation producing methane.
Numerically, you can't cut a lot of your GHG impact by reducing/switching meat consumption if you are living an ordinary middle class first world lifestyle in other respects.
Methane accounts for about 10% of warming from anthropogenic US GHG emissions. Enteric fermentation in ruminants accounts for 25% of that 10%, and agricultural manure another 10%. So you can cut maybe 25% of 10% (2.5%) from baseline-American emissions by eliminating red meat from your diet, or 35% of 10% (3.5%) by eliminating animal products altogether.
Agriculture accounts for 10% of emissions, and meat production is just a portion of that.
Personal dietary changes are at least quick and inexpensive, even if they don't lead to deep emissions reductions. I stopped eating red meat a few years ago because of a family history of heart attacks. It actually saved money on my grocery bills.
If you eat a lot of farm-raised beef and then start getting all those calories from chicken instead it will indeed be a significant reduction of your carbon footprint.
If you give up air travel, while you're at it, you might cut it just as much again, or more. (depending, of course, on how much you fly).
Cows are the only animals that can turn indigestible (for human) grasslands, and deserts, into rich, plant diverse carbon sinks that produce food for humans.
