PDF vs JPG: What’s the Real Difference?

Purpose and Design

Here’s the biggest difference that drives everything else: JPG is made for images, while PDF is made for documents.

When you take a photo with your phone, it automatically saves as a JPG because that format is specifically designed to handle the millions of colors and subtle details in photographs. JPGs excel at representing continuous-tone images like photos, artwork, and graphics with color gradients.

PDFs, on the other hand, were created to preserve the exact layout and formatting of documents, whether that’s a resume, contract, magazine, or ebook. Adobe designed PDFs to solve a specific problem: how do you share a document and ensure it looks identical on everyone’s computer, regardless of what fonts they have installed or what software they’re using?

What They Can Hold

A JPG file can only contain one single image. That’s it. Nothing more, nothing less. It’s a flat, two-dimensional image with no additional layers or complexity.

A PDF? It’s like a digital briefcase that can hold an entire office worth of materials. You can pack in:

• Multiple pages (hundreds or even thousands)
• Images in various formats (including JPGs!)
• Formatted text with different fonts, sizes, and styles
• Clickable hyperlinks and bookmarks
• Interactive forms that people can fill out
• Digital signatures
• Embedded fonts so text displays correctly everywhere
• Annotations and comments
• Tables, charts, and diagrams
• Audio and video files (in some cases)

This is why PDFs are perfect for reports, presentations, ebooks, magazines, and any multi-page document that needs to maintain its structure.

Quality and Compression

This is where things get technical, but I’ll keep it simple.

JPG uses what’s called “lossy compression.” In simple terms, it analyzes your image and throws away data it thinks you won’t miss to make the file smaller. The algorithm is pretty smart—it removes information in ways that are usually hard for human eyes to detect. But here’s the catch: every time you edit and save a JPG, it recompresses and loses a tiny bit more quality. It’s like making a photocopy of a photocopy—eventually, you’ll notice the degradation.

The amount of quality loss depends on your compression settings. You can save a JPG at high quality (larger file) or low quality (smaller file). Most cameras and phones use a good balance by default.

PDFs handle compression differently. They can include images in various formats and don’t necessarily compress them the same way. If you put a high-quality image in a PDF, it can stay high-quality. PDFs are particularly good at preserving the crispness of text and vector graphics (like logos and diagrams) because they can store these as mathematical descriptions rather than pixels.

Some PDFs also use compression, but you have more control over it. You can create PDFs that preserve maximum quality for professional printing, or compress them heavily for web sharing.

Editing Capabilities

Want to edit a JPG? You’ll need photo editing software like Adobe Photoshop, GIMP, or even simple apps on your phone like Snapseed or the built-in photo editor. With these tools, you can:

• Crop and resize the image
• Adjust brightness, contrast, and colors
• Add filters and effects
• Remove objects or blemishes
• Layer multiple images together (in advanced editors)
• Draw or paint directly on the image

You’re manipulating the actual pixels that make up the image.

Editing PDFs is a completely different story. While you can use PDF editors (like Adobe Acrobat, PDF Expert, or online tools) to change content, you’re working with the document structure rather than pixel-by-pixel editing. With PDF editors, you can:

• Edit or replace text (if the PDF isn’t locked)
• Add annotations, highlights, and comments
• Insert or delete pages
• Add or remove images
• Fill out forms
• Add digital signatures
• Redact sensitive information
• Merge multiple PDFs together

However, some PDFs are locked by their creators to prevent editing entirely. You might encounter PDFs that don’t allow you to copy text, print, or make changes. This is a security feature often used for contracts, official documents, and copyrighted materials.

File Size

JPGs are usually pretty compact, which is exactly why they became the standard for digital photography. The compression algorithm is efficient at keeping file sizes manageable. A typical smartphone photo might be 2-5 MB, while a heavily compressed JPG could be just a few hundred kilobytes.

PDFs vary wildly in size depending on what’s inside them. Here’s a rough idea:

• A simple one-page text document: 20-100 KB
• A 10-page report with some images: 500 KB – 2 MB
• A heavily illustrated ebook: 5-50 MB
• A high-resolution magazine or catalog: 50-200 MB+

The size depends on factors like the number of pages, image quality, embedded fonts, and compression settings used when creating the PDF.

Compatibility and Viewing

JPGs can be opened by virtually any device or software. Your computer’s default image viewer, web browsers, smartphones, tablets, digital photo frames—everything can display JPGs without any special software. This universal compatibility is one of JPG’s biggest strengths.

PDFs are also widely compatible, but they require a PDF reader. The good news is that most devices come with one pre-installed (like Adobe Acrobat Reader, Preview on Mac, or built-in browser viewers). You can read PDFs on computers, phones, tablets, e-readers, and even some smart TVs.

Security and Protection

JPGs don’t have built-in security features. Once someone has your JPG file, they can view it, edit it, and share it freely. The only way to protect a JPG is through external methods, like password-protecting a zip file containing the image.

PDFs offer robust security options:

• Password protection (requiring a password to open or edit)
• Encryption
• Permission controls (allowing viewing but not printing or copying)
• Digital signatures for authentication
• Redaction of sensitive information
• Watermarking

This makes PDFs ideal for sensitive documents, contracts, legal papers, and confidential business materials.