1. You’re looking for more nuanced and accurate responses

ChatGPT uses natural language processing (NLP) to understand, interpret, and mimic human language. OpenAI describes GPT-4 as “10 times more advanced than its predecessor, GPT-3.5. This enhancement enables the model to better understand the context and distinguish nuances, resulting in more accurate and coherent responses.” 

This is, in part, because GPT-4 is a much larger language model than GPT-3.5, which means it has a bigger number of parameters. These parameters represent bits of information that the model uses to understand and generate text. 

OpenAI doesn’t reveal the exact number of parameters used in GPT-4. However, according to Andrew Feldman, CEO of AI company Cerebras, GPT-4 was trained using around 100 trillion parameters. That’s an order of magnitude greater than GPT-3’s 175 billion parameters.

GPT-4 also has a longer memory than previous versions, adding to its ability to learn complex language patterns. While GPT-3.5’s short-term memory is around 8,000 words, GPT-4’s short-term memory extends to somewhere between 64,000 words and 128,000 words.

2. You want to use custom GPT bots

Upgrading your ChatGPT account to a Plus subscription gives you access to key features beyond general content creation, including priority access to new features, faster responses, access during peak times, and access to custom GPTs.

Since you can only use custom GPTs with GPT-4, access to the GPT Store is limited to ChatGPT Plus subscribers. The GPT Store features customized AI chatbots powered by GPT-4 that offer different skills, training, and custom instructions.

OpenAI replaced ChatGPT plugins with custom GPT bots, which perform much like the plugins did.

3. You want more than plain text responses

GPT-4 is not only more powerful than GPT-3.5, but it’s also multimodal, meaning it’s capable of analyzing text, images, and voice. For instance, GPT-4 can accept an image as part of a prompt and provide an accurate text response, generate images, and be spoken to and then respond using its voice. These are all important factors when deciding between ChatGPT and ChatGPT Plus.

For example, ChatGPT Plus can “view” an image of your refrigerator contents and provide you with recipes using the ingredients it sees. ChatGPT Plus subscribers can also upload documents for GPT-4 to analyze and make inferences or summaries. By default, ChatGPT Plus will answer you with text, but you ask it to generate an image for you.

When you ask GPT-4 to generate images, the LLM will leverage DALL-E 3’s capabilities to do so; there’s no need to switch to another website or modality. This image generation feature is only available in ChatGPT Plus.

4. You want current information

The free version of ChatGPT cannot access the internet. ChatGPT Plus, however, can do so and thus can provide more accurate answers. OpenAI integrated a “Browse with Bing” feature into GPT-4, which means that the AI chatbot can provide up-to-date information on current events.

When you ask GPT-3.5, or the free version of ChatGPT, a question, like, “What is the most powerful iPhone?,” it will likely say the iPhone 13 Pro Max, which launched in 2021. This is because it has only been trained on information leading up to January 2022, so its knowledge is limited to events before this knowledge cutoff.

If you were to ask GPT-4 the same question, it would likely respond with the iPhone 15 Pro Max, Apple’s latest high-end iPhone that debuted in September 2023.