Thus it is very important to know when to choose which one. Following will help you to choose which one suits your needs.
1. The Workbookhttps://resources.docs.salesforce.com/sfdc/pdf/forcecom_workbook.pdf
This is the most advertised way of learning salesforce before trailhead came into the picture. It is not the best one either. I will say it is just a sales pitch for developers to attract them towards salesforce by focussing only on easier items. But you will soon realise picture is not that rosy once you start developing actual apps.
2. Trail headThis wizard based approach is suited for people who had salesforce connection and know few things here and there. This is also not comprehensive way of learning salesforce if you are targetting certifications.
3. Platform fundamentalshttps://resources.docs.salesforce.com/sfdc/pdf/salesforce_creating_on_demand_apps.pdf
This is the real deal, it is 400+ pages of pdf which goes into depths of salesforce configurations and tuning. It is best for developers like me who wants to know everything before they start. It is the complete and best source of information if you are planning to go for certification.
For this blog I am going to walkthrough trail heads first and then the platform fundamentals just to follow my goal, you might have certification as your goal. Feel free to start on platform fundamentals , there is no dependencies on all those paths.
Hope it helps -Jim