Hi there! You are 50% right! 犬 and 狗 really have the same meaning which is dog. But the difference is that 犬 is the sicentific name of dog while 狗 is the common name. For example, you can see 犬 is written on the signage in the zoo, but we call the animal in the case 狗. By the way, if the dog is very lovely and smart, girls like to call them 狗狗(gou3gou) which means like doggie :)