Compare headlines 4 and 5. Why is there a difference in the two headlines even when they outline the same scientific research?

First, let's add the missing piece - the article

"Well, we haven't read the articles yet, but I have their titles here. You can read them," Alana said as she handed a paper to her mother with the following list:

1. Long-Term Cell Phone Use Spurs Tumor Growth

2. Mobile Phone Use and Acoustic Neuroma

3. Study Links Mobile Phones, Benign Tumors

4. Cell Phone-Tumor Link Found?

5. Study Indicates Mobile Phones Increase Tumor Risk

"Now I'm even more confused. Do cell phones cause cancer or not? Can I use mine or not?" asked Alisa impatiently.

"In my next class we're going to read the articles, so I will tell you everything then," concluded her sister.

Then the Answer to our question:

Both headlines 4 and 5 outline the exact same way, with little or no difference in the headline structure. On a closer look, we can infer that scientific research 4 looks less definite in a risk being found research. Unlike 5 which looks more definite in combining mobile phones with acoustic neuroma.