Great question! As a fresh grad diving into industrial automation, you're asking exactly the right kind of practical question. Beyond brand preference, here are the real-world differences you'd actually experience on a mid-sized packaging line:

1. Programming Environment & Learning Curve: Siemens' TIA Portal is considered more polished and integrated - it reduces project setup time by about 30% for complex systems. Mitsubishi's IQ Works/GX Works is functional but can be buggier. For a new engineer, TIA Portal's consistency might save you headaches.

2. Ecosystem & Integration: Siemens has stronger integration with their own drives, HMIs, and other automation components. In packaging lines where you need smooth coordination between PLCs, servo drives, and vision systems, Siemens' unified ecosystem can simplify troubleshooting and maintenance.

3. Communication Protocols: Siemens typically has better native support for PROFINET and PROFIBUS, which are common in European packaging equipment. Mitsubishi excels with CC-Link networks, more popular in Asian markets. Your line's existing equipment might dictate this choice.

4. Diagnostic Capabilities: The S7-1500 has more advanced built-in diagnostics and predictive maintenance features. For a packaging line where downtime costs money, better diagnostics mean faster troubleshooting when a bagger jams or a filler malfunctions.

5. Scalability & Future-Proofing: Siemens tends to be better for lines that might expand or integrate with Industry 4.0 initiatives. Their edge computing and AI capabilities are more developed if you're planning smart packaging solutions.

6. Local Support & Parts: Check what's common in your region. Siemens has stronger global support, but Mitsubishi might have better local availability and pricing in some areas.

For a mid-sized packaging line, I'd lean toward Siemens if you're integrating multiple systems and want easier maintenance. But if you're on a tight budget and dealing with simpler, standalone machines, Mitsubishi could work perfectly. The real difference comes down to how much integration headache you're willing to manage versus upfront cost savings.