Even if a lot of people would like online and offline business to be considered very different, reality is far from that.
Online business need you to do some learning. Yes, as offline business, you need to learn as you go and keep learning. You don't need to know it all to start, but you need to put some learning in your daily working time.
Online business need some funding. Yes, as offline business, you can start with nothing. But it's a lot easier when you can invest some money. Online, you can start a business with less then $100/month.
Online business is faster. No, it need as much time as an offline business to make a living online. You need to stay focus and work everyday.
Online business are scam. Yes and No, it's like a lot of offline business. There's scam and there's some great business also. As offline business, if you see stuff about becoming an instant millionaire, then it's a scam. There's no instant millionaire short cut online or offline. You'll have to work, sorry...
Online business advertising is cheaper online. Yes and Not, as in offline business, you can find lots of free advertising. But you'll have to invest a lot of time to make it work with those free ads. It's always better to do a mix of paid and free ads.
If you have a business online, you can't expand it offline. Wrong, you can expand your online business in your neighborhood if you want to. You can have your business card with the logo and the info to contact you and your business. You can create flyers to promote your business. You can do all you want. It's all up to you.
The main difference between online and offline business, is that you need a way to connect on the internet to make business online. That's it.