Financial Advisory Boutique vs IB Difference - Infrastructure & Energy

Hi Everyone, trying to understand the differences in the role of an Analyst at an Investment Bank vs that of a Big-4 comparable firm in the same sector. 

I currently work at an Infrastructure & Energy based financial advisory firm in their London office (been just over a year). Our firm is known in the sector for its financial modelling expertise - we tend to work with established Infra PE Funds such as Macquarie, Equitix, Foresight, etc. While my firm offers multiple services such as Operational Model Builds and review work, I have mostly been involved on transactions (currently working towards closing £950 million worth of transactions) - across (Buyside) M&A, Project Finance & Refinancing. 

In these projects I am working directly with transactions team of Infra Funds, am responsible for the financial model, sit on calls with (sell-side) IB teams, lenders, and other parties; assist the fund's transaction team in their internal Investment Committee process and support them on negotiation of term sheets. 

The key thing I wished to learn and understand was - what are the differences between my role and that of an Analyst at an Infrastructure & Energy team within an Investment Bank. I am getting a great exposure by working on some industry leading transactions in the country currently. I get to undertake significant responsibility in these deals as it's a lean team of 3, and I  enjoy the aspect of learning directly from some well established individuals in the industry on these projects. 

I was lately in talks with an Investment Bank, but along with the pay the hours are equally high, and there seemed to be a rigid heirarchy like Analysts mostly reporting to Associates. Thus, I was confused if joining a team given its an Investment Bank is even worth it - the directors of my firm trust me with my work and place me on key transactions, and I get to work directly with partners of infra funds. But equally at the same time, I want to do well for myself in my long term career. As I have not really worked at an Investment Bank,  I wished to understand the differences between my role and of an IB Analyst to make an informed career choice. 

Really look forward to the responses. Thanks!