If you’re building apps for phones or tablets, here’s a must-see discussion for you. We were able to corral Greylock’s John Lilly (who recently helped lead an investment in Instagram, right before it was acquired) backstage at Disrupt NYC earlier this week for a more casual conversation about the mobile app ecosystem and hardware. In this short talk, Lilly shared his views about the similarities and differences of building applications for mobile devices, taking care to point out that he sees many great entrepreneurs approaching the phone in a similar manner to how they approach the tablet. While the operating systems are similar on iPhone and other iOS devices (like iPad), for instance, the use cases, usage by time of day, and monetization opportunities are entirely different. Lilly encourages entrepreneurs to ask how to get their ideas on the homescreens of users’ phones and tablets.