Totally different, in my opinion. As others are saying above, the nylon Lonchamps totes are great for traveling, but fairly pricey compared to an average priced Coach bag. The nylon Longchamps are also very durable. I confess that I received one as a gift 10 years ago and have thrown it in the washing machine (not the dryer) more than once and it's held up just fine.
The Longchamps leather bags are quite pricey, comparable to the more expensive Coach leather bags (like this season's $898 bag). But the styles are completely different. So many factors to consider - what you will use it for, the aesthetic you prefer, the leathers you like...