What is the difference between free and paid SMS services?

Free SMS v/s Bulk SMS

Best free SMS services:

• way2sms - http://site21.way2sms.com/content/index.html
  
  
• afreesms - http://www.afreesms.com/intl/india
  
  
• sendsmsnow - http://www.sendsmsnow.com/

USAGE:

Free SMS- These services are used by students and people using SMS services temporarily or just for fun. You can send 50-100 SMS daily through these services.

Best paid SMS service: 

• MSG91- https://msg91.com/

USAGE:

Bulk SMS- These services are used by business organizations for OTP, alerts, and also for promoting their businesses. Through these services, you can send lacs of SMS in a single click.