Q. Are Arigato and Arigatogozaimasu different ?

Arigatogozaimasu is just a politer version of Arigato. Arigato is like Thanks and Arigatogozaimasu is like Thank you.
One tip when you say Arigato. It’s actually Aligato, not Arigato. Not exactly “L”, slightly weaker than L but definitely not “R”. There isn’t any R pronunciation in Japanese language even though we always use R when we spell. So it’s Kalaoke, not Karaoke. It’s Lyokan, not Ryokan !