The best way to attract as much attention as possible from recruiters is to keep both your resume and your professional social media profile up to date. However, there are significant differences in how employers use each of these options when it comes to finding candidates for a job. Your resume is important because it's the beginning of a deeper conversation about yourself. LinkedIn has a job board, of course, but many other sites that offer job offers will also integrate with LinkedIn.
You've likely found a job offer that allows you to use your LinkedIn profile instead of a resume to submit online job applications. Other important sections include your profile picture, education (if applicable), and the two most recent posts, which are heavily weighted based on the relevance and integrity of the keywords. According to LinkedIn, including your two most recent positions increases your chances of appearing in relevant search queries by more than 10 times. While you'll only have one LinkedIn profile that does the overall job of presenting your professional personality to the online world, you should ideally have a different resume for each position you apply for, each carefully designed to fit the requirements of each position.
Having the right keywords on your resume and the right keywords on LinkedIn will help you overcome these filters. Even if you apply for a job through your LinkedIn profile and capture the hiring manager's attention, they're likely to ask for your resume. While your resume and LinkedIn profile are important job search tools, they serve slightly different purposes and are read by slightly different audiences under different conditions. LinkedIn will require some adaptations, since you'll want to tell a specific story, but not to the same extent as your resume.
Connect with colleagues in your field and ensure that your resume and LinkedIn profile convey a coherent message around your experiences, skills, and value. Because of these similarities, copying the content of your resume directly to your LinkedIn profile is usually a good idea. It's also why a hiring manager will still ask you for a resume if you apply with your LinkedIn profile. Often, the person is qualified, but the resume (or LinkedIn profile) isn't formatted or optimized for keywords.
This is always the best option, since your resume is designed for the position, while your LinkedIn reflects your most important career goals. Last week I was working with a client who wanted to know where to focus: LinkedIn profile or resume.