Introduction:
SN1 reaction is a nucleophilic substitution reaction that occurs in two steps. In the first step, the leaving group departs from the substrate to form a carbocation, and in the second step, a nucleophile attacks the carbocation. In this process, the rate of reaction depends on the stability of the intermediate carbocation.

Comparison between CH3OCH2Cl and CH3OCH2CH2Cl:
CH3OCH2Cl and CH3OCH2CH2Cl are two different substrates that undergo SN1 reaction. The difference between these two substrates lies in the size of the alkyl group attached to the leaving group.

Explanation:
The rate of SN1 reaction depends on the stability of the carbocation intermediate. The stability of a carbocation increases with the size of the alkyl group attached to it. This is due to the inductive effect of the alkyl groups, which stabilizes the positive charge on the carbocation. Therefore, CH3OCH2CH2Cl will undergo SN1 reaction faster than CH3OCH2Cl because the former has a larger alkyl group attached to the leaving group.

In CH3OCH2Cl, the carbocation intermediate formed after the departure of the leaving group is a primary carbocation. Primary carbocations are less stable than secondary or tertiary carbocations due to the lack of alkyl group support. Therefore, the reaction rate is slower.

In CH3OCH2CH2Cl, the carbocation intermediate formed after the departure of the leaving group is a secondary carbocation. Secondary carbocations are more stable than primary carbocations due to the alkyl group support. Therefore, the reaction rate is faster.

Conclusion:
In conclusion, CH3OCH2CH2Cl will undergo SN1 reaction faster than CH3OCH2Cl due to the stability of the carbocation intermediate. The larger alkyl group attached to the leaving group in CH3OCH2CH2Cl stabilizes the positive charge on the carbocation intermediate and increases the reaction rate.