Hello Senthil,

1) ethernet is a multi access technology that using Media Access Control allows to connect multiple devices. Each device is addressed by its MAC address. An ethernet frame has a destination MAC address, a source MAC address, protocol type that says what upper layer protocol is carried inside.

Ethernet does not use a TDM framing structure: when no traffic is sent there is silence. Each frame uses a 64 bits preamble to allow to potential receivers to sync with the frame. Between two distinct frames a mininum inter frame gap is needed this is equivalent of 12 bytes on wire.

Serial is point to point in nature, when synchronous there is a framing structure the frame header, there is no equivalent of MAC addresses (point-to-point)

2)

A controller E1 object handles a PRI interface allowing to configure some aspects like linecode, CRC, framing type and how the B channels are used (one or more channel-groups can be configured). From controller configuration one or more serial interfaces objects are created like in your example.

It is a choice of IOS for this kind of modules that have many configurable parameters.

There are some other modules that  haven't a controller object and use service-module commands in interface configuration mode to configure linecode and other E1 aspects.

Hope to help

Giuseppe