I have this weird issue that hopefully can be explained to on why it is happening and how to rectify it. I got bored today and decided to toy around with EAC a tad just for learning purposes. I came across a new dilemma, the extracted WAV issue. I wanted to compare the same music mp3 file that was created in two different ways. Normally to rip an album, you put in the cd and extract the files. It auto converts to a VBR mp3 encoded in LAME v 3.90.3 w/ APS settings. So, I wanted to extract just a single file from my cd as a WAV. I then wanted to open that single WAV file to encode it to mp3 since I had taken the original cd out of my drive. I did the following process: I compressed the file by going to Tools, compress WAVs,selecting the wav file, then hitting open. EAC completed its compression. It created a VBR mp3 file that on the surface looked the same as a copy of the previously ripped mp3 But there were differences between the mp3 files. The single extracted WAV file from the cd earlier had different file size, average bitrate, and compression ratio than the ORIGINAL mp3 file created from the whole cd via Lame 3.90.3 w/ VBR alt preset standard. I don't understand why they would differ.
Here's the differences:

THis is the original mp3 file created from extracting the whole cd to wav then encoding to VBR APS mp3 format (encoded with Lame 3.90.3)

File Size: 5.74 MB
Average Bitrate: 259
Compression Ratio: 5 to 1



Here's the single extracted WAV file converted to mp3 via of the process of going to Tools, compress WAVs, opening WAV file. (encoded with Lame 3.90.3)

File Size: 5.73 MB
Average Bitrate: 215
Compression Ratio: 6 to 1



These are the same files, yet they have differences. I don't understand why. All I know is EAC is encoding the wav file differently for some reason. In summary, I know how to make high quality VBR APS mp3's when the cd is in the drive simply by hitting the mp3 button. But when I have WAV files in a folder somewhere, getting those converted to mp3 is more of problem and had caused the difference above like I mentioned. Any help/advice on why this happening and how to fix it is appreciated

Unless I'm missing something here, the second file is the same file size roughly, but much lower bitrate, meaning it has to be longer than the first file?

They are exactly the same length(time). Somehow EAC is encoding slightly different. Do adding wav files manually then compressing them use a slightly different scheme than just extracting them and having the program auto convert them to a pre-determined mp3 scheme( VBR in Alt Preset Standard)?

When you encode straight from CD, EAC may automatically add tags (if it's configured to do so), when you encode from WAV, EAC doesn't know what the CD is so it doesn't add tags, so maybe tags are the only cause of size difference?
You can decode both MP3s back to WAVs and do a bit-compare of them to see if there are any actual audio data differences between them.